UNIVERSITY OF CALIFORNIA
DEPARTMENT OF EDUCATION
GIFT OF THE PUBLISHER
No./<f<? Received /#4
LIBRARY
OF THE
UNIVERSITY OF CALIFORNIA.
GIFT OF
Class
From the collection of the
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Prelinger
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JJibrary
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San Francisco, California
2006
ELEMENTARY CHEMISTRY
A LAB OR A TOR Y MA NUA L
ELEMENTARY
CHEMISTRY
A LABORATORY MANUAL
By
C. E. LINEBARGER
Instructor in Chemistry in the
Lake View High School, Chicago,
and Editor of " School Science"
RAND, McNALLY & COMPANY
CHICAGO NEW YORK LONDON
vi Elementary Chemistry
the general work, the last few months of the course
being given to the simpler parts of it.
This Manual represents an attempt to fulfill the
above requirements. It contains more experiments
than can be performed in the usual course so as to
offer a considerable range and option. The Qualitative
Analysis is confined to the Appendix, and may well
serve as the basis for an advanced course.
The author takes pleasure in thanking the following
teachers for valuable criticisms on the manuscript :
Mr. Harry D. Abells, Morgan Park Academy, Morgan
Park, III.; Dr. C. E. Boynton, Robert Waller High School,
Chicago ; Miss Louella Chapin, South Division High
School, Chicago; Mr. Harry Clifford Doane, Central
High School, Grand Rapids, Midi.; Mr. Oscar R. Flynn,
Hyde Park High School, Chicago; Mr. Albert C. Hale,
Boys' High School, Brooklyn, N. Y.; Prof. Alexander
Smith, the University of Chicago; Mr. Charles M.
Turton, South Chicago High Scliool, Chicago; Prof.
Theodore Whittelsey, Northwestern University ; Mr.
C. M. Wirick, R. T. Crane Manual Training High
School, Chicago ; Mr. E. C. Woodruff, Lake View High
School, Chicago; and Mr. F. J. Watson, William
McKinley High Scliool, Chicago.
He also wishes to acknowledge his indebtedness to
the following teachers who have read the proofs of the
book and offered many helpful suggestions : Prof.
Alexander Smith, the University of Chicago; Prof.
G. C. Caklwell, Cornell University, Ithaca, N. Y.; Mr.
Charles M. Turton, South Chicago High School, Chicago;
Mr. E. C. Woodruff, Lake Vievv High School, Chicago.
His thanks are also due Mr. W. E. Davis and Mr.
E. C. Woodruff for the preparation of the illustrations.
C. E. LlNEBARGER.
Chicago, April, 1904..
THE TABLE OF CONTENTS
(Numbers of Experiments follow the Titles)
PAGE
Introductory i
Some Physical Properties of a Few Familiar Sub-
stances, i Chemical Properties of a Few Familiar Sub-
stances, 2 Physical and Chemical Changes, 3 Dry and
Wet Reactions, 4 Reactions in Gases, 5 Reaction Due
to Light, 6 Mixtures and Compounds, 7 Law of Con-
servation of Matter (Persistence of Mass), 8.
Oxygen ... 14
Oxygen from Silver Oxid, 9 Oxygen from Mercuric
Oxid, 10 Oxygen from Potassium Chlorate, from a Mix-
ture of Potassium Chlorate and Manganese Dioxid, n
Preparation of Oxygen from a Mixture of Potassium Chlo-
rate and Manganese Dioxid, 12 Oxygen from Sodium
Peroxid by Action of Water, 13 Properties of Oxygen, 14.
Ozone 21
Preparation of Ozone, 15 To Find the Weight of One
Liter of Oxygen, 16 To Find the Percentage of Oxygen
in Potassium Chlorate, 17.
Hydrogen 26
Hydrogen from Acids by Action of Zinc, 18 Proper-
ties of Hydrogen, 19 Transpiration of Hydrogen, 20
Combustion of Hydrogen, 21 Oxidation and Reduction,
22 Hydrogen from Water by Action of Sodium, 23
Hydrogen from Steam by Action of Magnesium, 24
Hydrogen from Steam by Action of Iron, 25 Hydrogen
from Solutions of Caustic Alkalis by Action of Aluminum,
26 Hydrogen from Sodium Hydroxid by Heating with
Iron Powder, 27 Hydrogen from Calcium Hydroxid by
Action of Iron Powder or Zinc Dust, 28.
Water 34
Dissolved Matter in Different Waters, 29 Distillation,
30 Coagulation Filters, 31 Conditions Effecting Solu-
tions, 32 To Determine the Solubility of Potassium
[vii]
viii Elementary Chemistry
PAGE
Dichromate in Water, 33 To determine the Solubility of
Air in Water, 34 Heat Effects of Solution, 35 Super-
saturation, 36 Water of Crystallization, 37 To Find the
Percentage of Water of Crystallization in Gypsum, 38
Deliquescence, 39 Efflorescence, 40 Test for Water, 41
- To'Ascertain the Volumetric Composition of Water, 42.
Hydrogen Dioxid 43
Hydrogen Dioxid by Action of Sodium Peroxid on
Water, 43 Hydrogen Dioxid by Action of Sulfuric Acid
on Barium Dioxid, 44 Properties of Hydrogen Dioxid, 45
- To Verify the Law of Definite Proportions by Weight,
46 To Verify the Law of Definite Proportions by Vol-
ume, 47 To Verify the Law of Multiple Proportions, 48.
Nitrogen and Its Hydrogen Compounds 47
Separation of Nitrogen from the Air, 49 Nitrogen by
the Decomposition of Ammonium Nitrate, 50 Nitrogen
from Potassium Nitrate by Action of Iron Powder, 51
Ammonia from Ammonium Salts by Action of Caustic
Alkalis or Lime, 52 Ammonia from the Destructive
Distillation of Some Animal Substances, 53 Preparation
and Properties of Ammonia, 54 Ammonia by the Inter-
action of Potassium Nitrate, Potassium Hydroxid, and
Iron Powder, 55.
Carbon 51
Formation of Charcoal, 56 Graphite from Pig Iron, 57
Preparation of Lampblack, 58 Density and Porosity
of Charcoal, 59 Adsorption of Gases by Charcoal, 60
Reduction by Charcoal, 61 Decolorizing Action of Bone-
black, 62 Combustibility of Different Forms of Carbon, 63.
The Compounds of Carbon with Oxygen 54
Carbon Dioxid a Product of Combustion, 64 Carbon
Dioxid Given Off in Respiration, 65 Carbon Dioxid Pro-
duced by Fermentation, 66 Carbon Dioxid from a Car-
bonate by Action of an Acid, 67 Properties of Carbon
Dioxid, 68 Action of Carbon Dioxid on Litmus, 69
Carbon Dioxid Absorbed by Sodium or Potassium Hydroxid
Solutions, 70 Carbon Dioxid in Solution Dissolves Cal-
cium Carbonate, 71 Carbon Monoxid by Action of Sul-
furic Acid on Sodium Formate, 72 Carbon Monoxid by
The Table of Contents ix
PAGE
the Action of Sulfuric Acid on Potassium Ferrocyanid, 73
Oxids of Carbon from Oxalic Acid, 74 To Find the
Weight of a Liter of Carbon Dioxid, 75.
Nitrogen and Hydrogen Compounds of Carbon .... 60
Methane from Sodium Acetate by Action of Soda-lime.,
76 Ethylene from Alcohol by Action of Sulfuric Acid, 77
Acetylene by Action of Water on Calcium Carbid, 78
Destructive Distillation, 79 A Simple Gas Factory, 80
A Candle as a Gas Factory, 81.
The Atmosphere 62
To Determine the Percentage of Oxygen in the Air, 82
Volume of Oxygen in Air, 83 Action of Dust on the
Precipitation of Water Vapor, 84 To Find the Weight of
a Liter of Air, 85.
Fire and Flame 66
Kindling Temperature, 86 Structure of Flame, 87
Luminosity of Flame, 88 Speed of Propagation of Flame,
89 Oxidizing and Reducing Flames, 90.
Salts, Acids, and Bases 68
General Properties of Acids, 91 General Properties of
Bases, 92 Neutralization, 93.
Oxids of Nitrogen ; Nitric Acid 69
Preparation and Properties of Nitrous Oxid, 94 Nitric
Oxid ; Its Preparation and Properties, 95 Volumetric
Composition of Nitric Oxid, 96 Nitrogen Dioxid, 97
Illustration of the Law of Volumetric Proportions, 98
Preparation and Properties of Nitric Acid, 99 Decompo-
sition of Nitric Acid by Heat, 100 Reduction of Nitric
Acid to Ammonia, 101 Reduction of a Nitrate to a
Nitrite, 102.
Preparation and Properties of Acids, Bases, and Salts . . 75
Preparation of a Salt by Direct Union of the Elements,
IO 3 Preparation of a Salt by the Solution of a Metal in
an Acid, 104 Preparation of a Salt by Neutralization of
Ammonium Hydroxid by Hydrochloric Acid, 105 The
Solubility Product, 106.
x Elementary Chemistry
PAGE
The Halogens and Their Hydrogen Compounds 78
Chlorin by Oxidization of Hydrochloric Acid, 107
Preparation of Chlorin, 108-109 Properties of Chlorin, no
Chlorin Water, in Preparation and Properties of
Bromin, 112 Preparation and Properties of lodin, 113
Tests for Free Bromin and lodin, 114 Action of Concen-
trated Sulfuric Acid on Halid Salts, 115 Preparation and
Properties of Hydrochloric Acid, 116 Analysis of Hy-
drogen Chlorid, 117 Tests for Chlorids, Bromids, and
lodids, 118 To find the Atomic Weight of Chlorin, 119
To Ascertain the Strength of a Given Sample of Hydro-
chloric Acid, 120 To find the Strength of a Given Sample
of Nitric Acid, 121.
The Alkali Metals 89
Properties of Sodium and Potassium, 122 Preparation
and Properties of Potassium Carbonate, 123 Preparation
and Properties of Sodium and Potassium Hydroxids, 124
Preparation and Properties of Ammonium Amalgam,
125 Solvay Process of Sodium Carbonate Manufacture,
126 Flame Tests, 127 Preparation and Properties of
the Nitrates_of the Alkali Metals, 128 Test for a Nitrate,
129.
Equivalent Weights 93
Equivalent of Sodium, 130 Equivalent of Zinc, 131
Equivalent of Magnesium, 132 Equivalent of Zinc, 133
To Determine the Vapor Density of Alcohol by Dumas'
Method, 134.
Sulfur and Its Compounds 97
Properties of Sulfur, 135 Preparation and Properties
of Hydrogen Sulfid, 136 Preparation of Sulfur Dioxid,
137 Properties of Sulfur Dioxid, 138 Properties of
Sulfurous Acid, 139 Properties of Sulfuric Acid, 140.
Phosphorus 100
Physical Properties of Phosphorus, 141 Conversion
of Red Phosphorus into Yellow Phosphorus, 142 Prepa-
ration and Properties of Phosphin, 143 Preparation of
Metaphosphoric Acid, 144 Preparation of Orthophos-
phoric Acid, 145 Reactions of Phosphates, 146.
The Table of Contents xi
PAGE
Arsenic and Antimony 103
Properties of Arsenic, 147 Arsin, 148 Arsenic Tri-
oxid, Trichlorid, and Trisulfid, 149 Arsenic Acid, 150
Properties of Antimony, 151 Stibin, 152 Antimony
Trioxid, Trichlorid, and Trisulfid, 153.
Bismuth 105
Properties of Bismuth, 154 Reactions of Salts of Bis-
muth, 155.
Magnesium 106
Properties of Magnesium, 156 Reactions of Mag-
nesium Salts, 157 Preparation of Magnesium Sulfate,
158 Preparation and Properties of Calcium Oxid and
Hydroxid, 159 Properties of Calcium Compounds, 160
Reactions of Strontium and Barium Salts, 161.
Boron and Silicon , 108
Preparation of Boric Acid, 162 Characteristic Reac-
tion of Boron Compounds, 163 Borax Bead, 164 Prep-
aration of Magnesium Silicid and of Silicon Hydrid, 165
Preparation of Silicic Acids, 166.
Zinc no
Properties of Zinc, 167 Reactions of Zinc Salts, 168
Blowpipe Reactions, 169.
Cadmium no
Properties and Reactions, 170.
Mercury in
Preparation of Mercury, 171 Mercurous Nitrate, 172
Mercuric Nitrate, 173 Reactions of Mercurous Salts,
174 Reactions of Mercuric Salts, 175.
Aluminum 112
Properties of Aluminum, 176 Action of Acids and
Alkalis on Aluminum, 177 Action of Mordants, 178
Alums, 179 Reactions of Aluminum Compounds, 180.
Tin 114
Physical Properties, 181 Crystallization of Tin, 182
Action of Acids on Tin, 183 Preparation of a Solution
of Stannic Chlorid, 184 Distinction Between Stannous
and Stannic Salts, 185 Replacement of Tin by Zinc, 186
To Determine the Equivalent of Tin, 187.
xii Elementary Chemistry
PAGE
Lead 116
Physical Properties of Lead, 188 Deposition of Lead
by Zinc, 189 Action of Acids on Lead, 190 Prepara-
tion and Properties of Lead Monoxid, 191 Preparation
and Properties of Red Lead, 192 Preparation and
Properties of Lead Dioxid, 193 Reactions of Lead Salts,
194 Action of Water on Lead, 195.
Copper 118
Properties of Copper, 196 Precipitate of Copper, 197
Preparation of Cuprous Oxid, 198 Reactions of Cop-
per Salts, 199 To Find the Equivalent of Copper, 200.
Silver 120
Preparation and Properties of Silver, 201 Reactions
of Silver Salts, 202.
Iron 121
Properties of Iron, 203 Reactions of Ferrous Salts,
204 Reactions of Ferric Salts, 205 Oxidation of Fer-
rous Salts, 206 Reduction of Ferric Salts, 207 Manu-
facture of Ink, 208 Borax Bead Test for Iron, 209.
Nickel 124
Reactions of Nickel Salts, 210.
Cobalt 124
Reactions of Cobalt Salts, 211 Analysis of a Nickel
Coin, 212.
Chromium and Manganese 125
Reactions of Chromic Salts, 213 Borax Bead Test for
Chromium, 214 Reduction of Chromates to Chromic
Compounds, 215 Properties of Chromates, 216 Reac-
tions of Manganous Salts, 217 Borax Bead Test for
Manganese, 218 Oxidation with Potassium Perman-
ganate, 219.
Some Organic Compounds 127
Preparation of Aldehydes, 220 Preparation of Ethyl
Acetate, 221 Preparation of Soap, 222 Fehling's Test
for Sugar, 223 Preparation of Oxalic Acid, 224 Prepa-
ration of Nitrobenzene, 225 Preparation of Aniline, 226.
The Table of Contents xiii
PAGE
APPENDIX A
Qualitative Analysis i
Introductory Hydrochloric Acid Group Hydrogen
Sulfid Group Ammonium Sulfid Group Ammonium
Carbonate Group The Alkali Metals : Ammonium,
Sodium, Potassium.
APPENDIX B
The Metric System of Weights and Measures .... xvii
APPENDIX C
Instruments for Weighing and Measuring xix
The Thermometer The Barometer Balances Grad-
uated Vessels.
APPENDIX D
Tables xxvi
Physical Constants of some of the Elements Tension
of Water Vapor Solutions to be Prepared.
APPENDIX E
Significant Figures and Forms of Record in Quantitative
Work xxxi
APPENDIX F
Laboratory Equipment xxxvi
List A, Individual Apparatus List B, Table Appa-
ratus List C, Demonstration Apparatus List D,
Chemicals.
EXPERIMENTS
INTRODUCTORY
EXPERIMENT i. Some Physical Properties of a
Few Familiar Substances. What information do
your senses of sight, of smell, of taste, of hearing, and
of feeling give you in regard to the following sub-
stances : Charcoal, sulfur, paraffin, common salt (sodium
chlorid), sugar, naphthalene (moth balls), borax, salt-
peter (potassium nitrate), alcohol ? Tabulate the results
of your observations in the form outlined below.
Put some (S mm - or i cm - circle 1 ) of each of the sub-
stances examined above in a test tube (a separate tube
for each substance), fill the tube a third full of water,
and note whether the substance sinks or swims. Shake
the substance and water well together 2 and see if it
dissolves. Heat the water to boiling 3 in the flame of a
Bunsen burner 4 and note anything that happens. Set
the tubes aside until cold (leave the one containing
the charcoal for several hours) and note any changes.
Tabulate your observations in the form outlined below:
Behavior in
Water
SUBSTANCE
Sight
Smell
Taste
Hear-
Feeling
Specific gravity,
solubility, etc.
ing
Cold
Hot
color
odor
sweet
ring
hard
opacity
sonr
thud
soft
etc.
etc.
etc.
[I]
Elementary Chemistry
Fig. I ONE WAY OF SHAKING THE CONTENTS
OF A TEST TUBE
Which of your senses gives you the most information ?
What tests serve to identify each of the substances?
NOTE i. Estimation of Amounts of Substances. Many chem-
icals come in powdered form or may be easily reduced to a powder.
If a circle of given diameter be drawn on a piece of paper and as
much of the powder as
possible placed upon it so
as to form a conical heap
whose base is the circle,
fairly definite amounts of
the powder are obtained.
In the directions the
diameter in centimeters
is given right after the
weight in case the sub-
stance in use is a powder;
as, (s cm - circle). If the
substance is not powdered
and it is not convenient
to reduce it to a powder,
the amount may be expressed in terms of the size of a single piece;
this is given in millimeters. Thus, bim. means that a piece
should be selected or prepared that is equivalent in size to one of
spherical shape &mm. \\\ diameter.
Such estimations need not be made
very accurately, as even rather
wide deviations will not essentially
affect the experiment.
Note that the unit employed in
designating amounts of powders is
centimeters, while that used in
denoting the size of single pieces is
millimeters.
NOTE 2. To Shake a Liquid
and Solid Together in a Test
Tube, (i) Gently tap the rounded
end of the tube held as horizontally
as possible in the palm of the hand
(Fig. i). (2) Close the tube with
the thumb and invert it. The first
method is to be used when the
liquid is hot or corrosive.
NOTE 3. Handling Test Tubes.
Test tubes may be held by the
upper end in the lingers (Fig. 2)
generally without inconvenience,
but if the liquid is to be boiled for
some time or the substance is to be heated to a high temperature
in the test tube, it may be grasped and held with a test tube
holder, several forms of which are on the market. A serviceable
Fig. 2 TEST TUBE-HEED IN THE-
FINGERS
Experiments
test tube holder may readily be made of rather stout wire, the ends
of which are twisted into coils into which the tube just fits, while
the middle part is twisted together and inserted in a handle of
wood or cork (Fig. 3). A substitute for a test
Fig. 3 TEST TUBE
HOLDER
tube holder is a strip of paper folded and passed
around the test tube just below its mouth so
that the two ends of the paper may be held
between the thumb and forefinger (Fig. 4) or
by tongs (Fig. 5).
In heating test tubes containing a liquid, the
outside of the tube must be dry and the glass
heated uniformly and gradually. It should be
held in the upper part of the flame and should
at first be passed to and fro through it. The
flame should never be allowed to touch any
part of the tube which is not covered on the
inside with the
liquid, as the
bare glass may
become so high-
ly heated that
if the compara-
tively cold liquid touches it, it may
break. When a liquid is being
boiled vigorously in a test tube, it
sometimes happens that portions
of the hot liquid are thrown out of
the tube with considerable force.
This may be avoided by holding
the tube in an inclined position
and continually rolling it to and
fro and moving it around in the
flame. Be very careful always to
hold the mouth of the tube away
from yourself as well as your neigh-
bors, so that in case the liquid does
spurt out, it will not harm any one.
Test tubes should always be
cleaned as soon as possible after
using. A test tube swab or cleaner which compares favorably
with the bristle ones sold by the dealers may be made out of a
wooden stick with a bit of sponge or rag tied over its end.
NOTE 4. Bunsen Burners. Bunsen burners are not only an
indispensable source of heat in all laboratories provided with gas,
but are also used in slightly modified form in gas stove and
"Welsbach" burners. The construction of a Bunsen burner is
shown in Fig. 6. The gas enters at e and passes up through
the opening at in into the tube n. Air is drawn in through the
holes at the base of n, and mixes with the gas. These holes can
be more or less closed by means of a ring 0, perforated with two
corresponding holes a. The mixture of gas and air issuing from
Fig. 4 TEST TUBE HELD BY
STRIP OF PAPER
Elementary Chemistry
1
Fitf. 5 TEST TUBE HELD BY STRIP OF PAPER
GRASPED BY TONGS
the top of the tube burns with an almost non-luminous flame.
When the supply of air is cut off by turning the ring b, the flame
becomes luminous and
smoky.
To put a Bunsen burner
in good condition, unscrew
the tube , and clean, if
necessary, the gas tip at
m. The ring should move
freely around the tube.
Put the burner together
again and, connecting e
with the gas supply by
means of rubber hose of
suitable length, open wide
the gas cock. As soon as
the gas seems to be escap-
ing freely, light it. If the
burner is in order and the
airholes at in are wide
open, the flame should be
blue, with the exception of a minute yellow spot near the top of the
flame. If this spot does not appear in the
^ flame, partially close the airholes until it is
seen. If the flame is at all luminous, even
when the airholes are wide open, the supply
of gas is too great for the supply of air. So
unscrew the tube n, and make ;;/ a little
smaller by pinching or hammering it together
somewhat. If the flame is too small and
burns with a hissing noise, open ;;/ a little.
Never use a burner unless it is in perfect work-
ing condition. If the gas supply is insufficient,
the flame will often "strike back," /. e., the
gas will burn at m instead of d. When this
occurs the tube n soon becomes so hot that it
cannot be handled, and the flame appears
green and smoky, and emits an unpleasant
odor. As soon as you find that a flame has
" struck back," cut off the supply of gas, and
after a minute or so relight.
EXPERIMENT 2. Some
Chemical Properties of a
Few Familiar Substances.
Put a piece (3 mm.^ o f charcoal
in a clean iron spoon and
hold it in a Bunsen flame
(Fig. 7). Observe carefully
Fig. 6 BUNSEN BURNER
Experiments
the behavior of the charcoal. Heat as hot as possible
until no further change is manifest. Go through similar
operations with the substances used in Experiment i,
taking a piece not larger than 3 mm -, and noting the
appearance of flame, color, and odor of fumes, appear-
ance and relative amount of ash, and in case the sub-
stance does not seem to burn, whether it swells up
or melts. Which of
the substances are not
changed chemically ?
What tests can you
add to those you found
in Experiment i ?
EXPERIMENT 3.
Physical and Chem-
ical Changes, (a)
Hold a piece of plati-
num wire in a Bunsen
flame for a minute or so,
and note what occurs.
Let the wire cool and
see if it has been per-
manently changed.
(b) Go through the
same operations as in
(#), using magnesium
Wire Or ribbon instead Fig - T-HEATING A SUBSTANCE IN A SPOON
of platinum. Compare restilt with that obtained in (a).
Compare the nature of the changes in (a) and (b).
(c) Wind tightly around one of the ends of each
of two electric light carbons (not "coppered") about
10 cm - of pieces of copper wire about \$cm. long. Con-
nect the other ends of the wires with a source of elec-
tricity and immerse the lower halves of the carbons
in a strong solution of copper sulfate (blue vitriol)
Elementary Chemistry
contained in a beaker or tumbler (Fig-. 8). Keeping
the carbons about a centimeter apart, let the current
pass for a few minutes. Then remove and examine
the carbons. Is there any evidence that a chemical
change has taken place ? Are both carbons affected in
the same way ? Compare this result with that obtained
by causing a current of electricity to pass through a
wire (incandescent bulb).
(d) Place a little (2 cm - circle) table salt in a test
tube and half fill the tube with water. Close the tube
with the thumb and shake until most of the salt has
disappeared. Filter 5 , catching the filtrate (the liquid
which passes through the paper) in a clean evaporating
dish. Does the filtrate taste salty ? Set the dish on a
ring of a retort stand
(Fig. 9) and heat, using
a large flame and play-
ing it around so that
the dish is heated uni-
formly and the bottom
not more than the
sides. Conduct all
Fig. 8 ELECTRIC LIGHT CARBONS CONNECTED
WITH A BATTERY BY MEANS OF COPPER
WIRES AND IMMERSED IN A COPPER SUL-
WITH A BATTERY BY MEANS OF COPPER r ~ rp ,f ,-, 11 -rr Qn fV, p f n nn A
^ S
FATE SOLUTION
o f t ft Q liquid may
spatter out of the dish and be lost. As the water boils
away a white substance is deposited, w^hich, when most
of the water has been driven off, crackles or decrepitates.
The decrepitation is due to particles of the solid enclos-
ing minute amounts of water, which are expelled with
explosive violence when the solid is heated. When the
decrepitation ceases let the dish cool and examine its
contents. Give all your reasons for thinking it to be
the substance you take it to be. Are the changes phys-
ical or chemical ?
Experiments
(c) Put some (2 cm - circle) powdered marble in a
test tube about a third full of water. Close the tube
with the thumb and
shake well. Does any
of the marble seem to
dissolve ? Decant the
liquid, i. e., pour it off
from the solid so as to
have as little as pos-
sible of the latter go
with it, on a filter (Fig.
10), and catch the fil-
trate in a clean evap-
orating dish. Heat
the dish as directed in
(d) until no more
liquid is left. Is there
more than a trace of
a solid residue ? What do you conclude about the solu-
bility of marble in water ? Pour 6 enough dilute hydro-
chloric acid on the marble left
in the test tube to fill it about
one-fourth full. Warm gently
so as to keep up a brisk evolu-
tion of gas. When the effer-
vescence ceases filter through
a fresh filter paper and catch
the filtrate in a clean evapo-
rating dish. Now heat the
liquid and evaporate it to dry-
ness. Is there any decrepi-
tation ? Cautiously taste a bit
of the residue not larger than
a pin head. Does it taste
salty ? Point out the physical
Fig. 9 EVAPORATING TO DRYNESS WITH FREE
OR BARE FLAME
Fig. 10 FILTERING
Elementary Chemistry
2 3
Fig. II SUCCESSIVE STEPS IN FOLDING A FILTER PAPER
and chemical changes. Let the dish containing the
residue stand for at least twenty-four hours and then
examine it. It will probably have attracted moisture
from the air and will be moist or even liquid if the
amount of water attracted is sufficient to dissolve it.
The substance is on
this account said to be
deliquescent; its name
is calcium chlorid.
Fig. 12 POURING LIQUID FROM A BOTTLE
INTO A TEST TUBE
NOTE 5. Filtering.
Filter paper is fitted into
a. funnel as follows : The
paper is folded to form a
semi-circle and then a
quarter of a circle (Fig. 1 1).
Three of the quarters are
separated from the fourth so as to form a cone which is fitted into
the funnel, wetted and smoothed around so as to fit the funnel.
When pouring a liquid on a filter, direct the stream of liquid so
that it strikes against the side of the paper cone and not into the
apex, otherwise there is danger of splashing. (Fig. 10.)
The stern of the funnel should touch the inside of the receiver
of the filtrate so as to
prevent the formation of
drops which by their fall
might occasion splashing.
NOTE 6. Pouring a
Liquid from a Bottle. In
pouring hold the bottle in
the right hand with the
thumb close to the label
and the little finger under
the bottom (Fig."i2). Re-
move the stopper with the
second and third fingers
of the left hand, the thumb
and first finger of which
Fig. 13 POURING FROM ONE BOTTLE INTO
ANOTHER
Experiments
hold the test tube or other receptacle. Remove the drop of liquid
that may adhere to the lip of the bottle by touching it with the
stopper, replace the stopper and return the bottle to its proper
place. The stoppers and bottles may also be held as shown in Fig.
13. Stoppers should never be placed upon the table top except in
extreme cases, and then only upon a piece of clean paper or glass.
EXPERIMENT 4. Dry and Wet Reactions, (a] Rub
together in a dry mortar a pinch of mercuric chlorid
with a pinch of potassium iodid.
What is the color and solubility
of the product ?
(b) Dissolve a pinch of mer-
curic chlorid in enough water to
fill a test tube about half full ;
also a pinch of potassium iodid
in about the same volume of
water in a second test tube. Mix
the solutions. How does the
color and solubility of the prod-
uct compare with that obtained
in (a) ? In which case does the
reaction take place the more
rapidly ?
(c) Mix together on a piece
of dry paper about equal bulks
(3 cm - circle) of powdered sodium
bicarbonate (baking soda) or
sodium carbonate (washing
soda) with powdered tartaric or
oxalic acid. Is there any appa-
rent change ? Put the mixture
in a beaker a fourth full of
water. What happens ?
EXPERIMENT 5. Reactions in Gases. Select two
wide-mouthed bottles or jars of the same size. Put in
one a couple of drops of strong hydrochloric acid and
Fig. 14 CYLINDRICAL JARS
PLACED MOUTH TO MOUTH
io Elementary Chemistry
cover the mouth of the bottle with a card. Likewise
put a couple of drops of strong ammonia water in the
other. Move the covered bottles around so that as
much of their inside surfaces as possible may be wetted.
Both the liquids give off vapors which are thus made to
fill the bottles. Place one bottle on the other in an
inverted position (Fig. 14) and slip out the cards. What
evidence is there that a reaction has taken place ? What
is the nature of the product ?
EXPERIMENT 6. Reaction Due to Light. Procure
a piece of blue-print paper which has not been exposed
to a strong light and tear it in two. Place one of the
halves between the leaves of a book so as to keep it
from the light and expose the other for ten minutes to
direct sunlight, or if that be not available, leave it on
the desk until the next laboratory period. Place both
pieces of paper in a dish and run water over them to
wash out any soluble coloring matter and compare the
color of the two pieces. What evidence is there that a
chemical reaction has taken place ?
EXPERIMENT 7. Mixtures and Compounds. I.
(a) Put a pinch of powdered iron or clean and fine
iron filings on a piece of smooth paper and move one
end of a bar magnet over the underside of the paper
just beneath the iron. Can the iron be drawn from
one part of the paper to another ?
(b) Perform a similar experiment with powdered
sulfur instead of iron.
(c) Put a pinch of powdered iron in a small test
tube and pour over it enough carbon bisulfid to fill the
tube about an eighth full. Shake thoroughly. Does
the iron seem to dissolve?
(d) Decant the liquid into a watch glass and allow
it to evaporate in the hood or out of doors. Is more than
a trace left ?
Experiments I I
(c) Repeat (c) and (d) with powdered sulfur instead
of iron. What is the residue ? How do you know ?
(f) Compare the solubility of iron and sulfur in
carbon bisulfid.
(g) Put a pinch of powdered iron in a small test
tube and cover it with dilute hydrochloric acid. What
occurs ? Note particularly any odor. Wet a small piece
of filter paper with a few drops of lead acetate solution
and cover the mouth of the test tube with it. Does it
change color ?
(//) Repeat (g) with sulfur instead of iron. Com-
pare the solubility of iron and sulfur in hydrochloric
acid. Are the above tests sufficient to distinguish iron
from sulfur?
(i) Weigh out 5.6 ff- of powdered iron and 3.2 & of
powdered sulfur and mix them thoroughly in a mortar.
What is the color of the mixture ?
(j) Place a pinch of the mixture on a piece of
paper and see if you can separate the iron from the
sulfur by moving a magnet under it as in (a).
(k) Put a little of the mixture in a small dry test
tube, add carbon bisulfid and shake thoroughly. Decant
upon a dry filter and catch the filtrate in a watch glass.
What is left after the carbon bisulfid evaporates ? Com-
pare with (d) and (c).
(/) Place a pinch of the mixture in a test tube and
add dilute hydrochloric acid. Compare with (g) and (//).
(;//) Now put all of the mixture that remains in
a rather small dry test tube and, using a test tube
holder, hold just the rounded end of the tube steadily
in the tip of a Bunsen flame until the lower part of the
mixture begins to glow. Then immediately remove
the tube from the flame.
(n) When the test tube is cool lay it on a piece of
paper and break it by tapping it with a pestle. Separate
12 Elementary Chemistry
the substance from the particles of glass and pulverize
it in a mortar. Compare its appearance with that of the
sulfur and iron and their mixture before heating.
(o) Place a pinch of the product on paper and test
it with a magnet as in (a) and (/). Compare with (a).
(p) Treat a little with carbon bisulfid as in (c), (d),
and (k). Result?
(</) Add hydrochloric acid to another portion as
in (), (/?), and (/). Note the smell of the gas and its
action on lead acetate paper. Compare with (g) and
(//). Point out all the chemical and physical changes
in this experiment. Are the properties of the product
from (;//) different enough from those of iron and sulfur
to characterize it as a new substance ? Why were defi-
nite amounts of the two elements taken ?
II. (a) Examine some gunpowder for its physical
properties ; apply the tests used in Experiment i. Place
a pinch of gunpowder in a spoon and heat it as you
did in Experiment 2 ; be careful not to lean over the
spoon, as the powder may flash up into the face. Put
about 3 ff- (3 cm - circle) of gunpowder in a test tube and
add enough carbon bisulfid to fill the test tube about
a quarter full. Filter through a small, dry filter paper
and catch the filtrate in a clean watch crystal. Set in
the hood to evaporate and determine by appropriate
tests what the residue is.
CAUTION. Carbon bisulfid forms with air an
explosive mixture. Do not neglect to extinguish
all flames within a yard of you before using it.
(b] Spread out the filter paper and shake out upon
it the residue in the test tube, so that the carbon bisul-
fid may evaporate.
(r) Put this residue in a test tube and fill about one-
third full of water. Shake the solid and the liquid
Experiments
together thoroughly, and heat for a moment to boiling.
Filter into an evaporating dish, and evaporate to dry-
ness over a bare flame.
(d) Examine the residue obtained as in Experiments
i and 2. Give all your reasons for thinking it to be the
substance you take it to be. Shake the black substance
remaining in the test tube out on the filter paper and
spread it out so
that the water
may evaporate.
(c) Examine
the residue when
dry to find out
what it is, and
give your proofs
for what you take
it to be. Into
how many con-
stituents have
you decomposed
or analyzed gun-
powder ? Which
Fig. J S CHASLYN BALANCE AND ERLENMEYER FLASK
Used in illustrating Law of Conservation of Matter
of them are ele-
ments ?
(/) Put some (i cm - circle) saltpeter in a mortar, add
about half its btilk of sulfur and grind the substances
to a fine powder. Add an equal bulk of charcoal and
grind all well together, but do not use too great a pres-
sure. Put a pinch of the mixture in a spoon and apply
a flame. What happens ? What new substance have
you prepared from saltpeter, sulfur, and charcoal ? Is
it a mixture or a compound ?
EXPERIMENT 8. Law of Conservation of Matter
(Persistence of Mass). Fit an Erlenmeyer flask with
a tight stopper and fill the flask about a third full of
14 Elementary Chemistry
strong lead acetate solution. Fill a test tube which is
small enough to slip inside the flask with a strong solu-
tion of ferric chlorid and carefully put it in the flask so
as not to mix the two liquids. Insert the cork tightly
and counterpoise the whole on a balance. (Fig. 15.)
Then tip the flask upside down so as to mix the two
solutions and, placing the flask again upon the balance
pan, see if the equilibrium has been destroyed. What
evidence is there that a chemical action has taken
place ? Wherein does this experiment illustrate the
law in question ?
OXYGEN
EXPERIMENT 9. Oxygen from Silver Oxid. Put
some (2 cm - circle) silver oxid in a test tube and, holding
the tube with tongs (Fig. 5), heat it in a Bunsen flame.
Bring a splinter of wood with a spark on its end into
the mouth of the test tube from time to time and note
what happens. Heat until the brown powder is turned
into a white mass. How can you prove this to be
silver ? How do you know that a gas is given off ?
EXPERIMENT 10. Oxygen from Mercuric Oxid.
Put enough mercuric oxid in an ignition tube 7 to fill
it to the depth of about a centimeter. Grasping the
tube with a test tube holder, heat it in a Bunsen flame,
very gradually raising its temperature as high as pos-
sible. Note any change in the color of the powder as it is
being heated. When the tube is red hot, insert (with-
out removing it from the flame) a splinter of wood with
a spark on its end. What happens? How do you
account for it ? After the tube is cool, what is the color
of the mercuric oxid which is left ? Is this change of
color of a physical or a chemical nature ? Examine the
deposit (sublimate} in the upper part of the tube, and
find out by its physical properties what it is.
Experiments 1 5
NOTE 7. Ignition Tubes. Ignition tubes are made of a spe-
cial kind of glass, often called "hard glass," which can with-
stand a very high temperature without melting. They should
be heated very gradually, as, being made of thicker glass than
ordinary test tubes, they are liable to break the more readily
when heated.
To make an ignition tube, choose a piece of hard glass (thick-
walled ordinary glass will do) about 8 mm. i n diameter, $mm. in
bore, and 12 to \^cm J long. Heat the tubing in the middle in a
Bunsen flame (better, a blast lamp flame) just above the yellow
spot, holding the ends in either hand and rotating the tube so as
to heat it uniformly. As soon as the glass begins to soften and
yield a little, pull it apart a little, keeping it in the flame and
rotating it all the while. Draw it apart very slowly so that the
glass of the closed end may be thick enough. When the tube
separates hold one part up with its closed end in the flame so that
it may be rounded off a little and, removing the tube from the
flame, blow gently into it so as to make the end slightly bulb-
shaped. Let the tubes cool very slowly, /. e. t anneal them by
closing the airholes of the burner, and holding them in the
smoky flame until they are covered with a deposit of soot.
EXPERIMENT IT. Oxygen from Potassium Chlo-
rate, and from a Mixture of Potassium Chlorate
and Manganese Dioxid. Fill a test tube to a depth
of about 2 cm - with potassium chlorate, and holding it
with a test tube holder, heat the rounded end in a
Bunsen flame. When the solid melts and effervesces
freely, insert a glowing splinter of wood into the mouth
of the test tube. Drop little bits of wood (not more
than 2 mm.} down into the effervescing melt. What
happens ?
Remove the test tube from the flame and as soon
as the effervescence ceases, slide a pinch (be sure not to
use too much) of powdered manganese dioxid from a
creased paper into the melted potassium chlorate. In
what way does the result show that a mixture of potas-
sium chlorate and manganese dioxid gives off oxygen
at a lower temperature than the former substance
alone? WhenUhe tube is cool, fill it with water and
let it soak for several hours ; the melt may then be
easily removed.
i6
Elementary Chemistry
EXPERIMENT 12. Preparation of Oxygen from a
Mixture of Potassium Chlorate and Manganese
Dioxid. Mix about 30^- (^cm, circle) of powdered
potassium chlorate with about a third of its bulk of
manganese dioxid and transfer to a dry flask (200 to
300 c - c -}. Bore a hole through a cork 8 , fitting the neck
of the flask so that an L-tube 9> ! may be pushed
through it. Slip over one branch of the L-tube one
end of a piece of rubber tubing about 30 cm - long, whose
other end is slipped over a delivery tube ! ! . Set the
flask on a wire gauze ] 2 on a ring of a stand and secure
the neck of the flask with a second ring (Fig. 16).
Alternate Apparatus. (Fig. 17.) A retort is pro-
vided with a delivery tube and is supported on a ring
stand over a wire gauze or sand bath 1 2 .
Place the mixture in the flask or retort, and heat
with a small flame, removing the flame if the evolution of
the gas becomes
too brisk. Collect
five receivers full
by water displace-
ment 13 , and pass
to Experiment 14.
NOTE 8. To Per-
forate Corks. To
perforate a cork, a
round ("rat-tail") file
about i$cm. long is
required. A cork is
chosen of such a size
that its narrower end
fits a little loosely in
the neck of the flask, retort, etc. The cork is softened in a cork
squeezer or by rolling it on (i) the table top under a board ; or (2)
on the floor under the sole of the shoe. The tip of the tang of
the file is heated to redness and the red-hot point used to burn a
small and regular hole through the axis of the cork. This hole is
then enlarged with the file until the glass tube can just be passed
through it by employing a twisting motion.
Fig. l6 HEATING A SUBSTANCE IN A FLASK AND
COLLECTING THE GAS EVOLVED
Experiments
Fig. 17 HEATING A SUBSTANCE IN A RETORT AND COLLECTING THE GAS EVOLVED
BY WATER DISPLACEMENT
Cork borers may also be used. These are tubes of brass or
steel, with a cutting edge, and are of various sizes, so as to cut a
hole of very nearly the desired diameter at once.
NOTE 9. To Cut Glass Tubing. To cut glass tubing, a three-
cornered file about 25 cm. long is needed. The tube is laid flat
upon the table, and a deep scratch made with the file at the point
where the tube is to be cut. The tube is then grasped with the
two hands, one on each side of the scratch, while the thumbs are
brought together just at the scratch, but on the side opposite.
While the fingers are pulling on the tube in the direction of its
length, a slight push with the thumbs across the axis of the tube
usually suffices to break it squarely off.
When a piece of glass tubing is cut the ends have sharp edges
which may cut rubber tubing slipped over them. The edges
should be smoothed down or " fire polished" by gradually heating
them in a flame, all the while twirling the tubing so that the
edges are heated uniformly, until the glass softens and the sharp
edges become rounded off, but care should be taken that the bore
of the tube is not at all lessened.
NOTE 10. To Bend Tubing. To bend glass tubing, hold it in
a flat luminous flame, such as that offered by an ordinary gas jet
(a so-called "bat-wing," "fish-tail," or "wing-top" may be put
on the Bunsen burner). Rotate the tube and move it to and fro
so as to heat a portion of the tube at least ^cm. in length. When
the tube begins to soften let it almost by its own weight bend
around to the desired shape. Do not try to bend it suddenly or
apply any considerable force. The bend should be very gradual
and the bore of the tube remain unchanged in the bend. Always
i8
Elementary Chemistry
" fire-polish " the ends of the tube. Such a tube is often called an
"L-tube," from its resemblance to the letter L.
NOTE ii. Putting Apparatus Together. In putting together
the parts of an apparatus, it is very necessary that they make
tight joints. The corks should be well softened and the tubes
inserted firmly. It is a good plan to lubricate glass tubing with
glycerin, vaseline, or even water. The best way to test an
apparatus for gas-tightness is either to compress the air in it by
blowing or draw some out by suction. As usually some part of
the apparatus is
under water, the
water will thereby be
made to rise or fall in
a tube, and if there is
any leak, this water
will change its level
when the opening
where the lips were
applied is closed. To
attempt to use leaky
apparatus is to lose
time and labor, and
to insure the failure
of the experiment.
NOTE 12. Heat-
ing Glass Vessels.
In heating glass ves-
sels, wire gauze (best
of copper) is usually
employed. Sand
baths may also be
used, and consist of
a shallow iron dish containing a little sand. Serviceable ones
may be made out of tin-pail or tin-can covers. Squares of asbestos
paper are also used in many laboratories. The object of thus
interposing a screen is to distribute the heat and render the glass
less liable to crack.
NOTE 13. Collecting Gases by Water Displacement. This
method consists in filling wide-mouthed vessels brimming full of
water, covering them tightly with a piece of paper, cardboard
or glass, inverting them with the cover pressed against the mouth,
placing them mouth downward in a dish filled with water (techni-
cally named a pneumatic trough), and removing the cover. The
pressure of the atmosphere keeps the water in the vessels, or
receivers, as they are commonly called. Most pneumatic troughs
are provided with a shelf less than an inch below the surface
of the water (Fig. 17), on which the receivers are set. The gas
which is evolved is made to pass up into the receiver by means of
a delivery tube, and to displace the water.
Only gases which are but slightly soluble in water can be col-
lected by water displacement.
Fig. 1 8 STOPCOCK FUNNEL GAS GENERATOR AND
CYLINDER FOR COLLECTING THE GAS
Experiments
Fig. 19 HOME-MADE
STOPCOCK FUNNEL,
NO. I
EXPERIMENT 13. Oxygen from Sodium Peroxid
by Action of Water. Fit a dry flask (200 to 300^-)
with a delivery tube and stopcock fun-
nel 14 . Place about 20^- ( 7 cm - circle) of
sodium peroxid in the flask and allow
water to drop slowly upon it from the
funnel. Collect five receivers full by
water displacement 13 and pass to Ex-
periment 14.
NOTE 14. Gas Generators. Gas gener-
ators are employed when a gas may be formed by the interaction
of a solid and a liquid. Of these there are many styles, of which
those provided with a stopcock funnel are the best, but stopcock
funnels are expensive. A serviceable stopcock funnel may be
made by the student as follows : Choose a piece of rubber tubing
that will just slip into the stem of a funnel and cut off a piece
about -2cm. long (Fig. 19). Cut a hole about i mm - in diameter
near one end and, warming the rubber a little, rub cement (made
by melting in a dish two parts of beeswax with one of rosin)
around trie lower half so as to form a thin coating. Very
cautiously (remember that funnels are made of thick glass and are
very liable to break if heated rapidly or unevenly) warm the stem
of the funnel where it commences to flare out and push the rubber
tube into it. When the glass is cold the cement
will hold the rubber in position very firmly. Put
a little vaseline on a glass rod 15 that slips easily
but snugly into the rubber tubs. To close the
stopcock, push the rod down so that it may cover
the lateral hole. To open it, raise the rod more or
less so as to uncover more or less the hole. Such
a stopcock cannot of course be used with liquids
which have any action on rubber. Pick out a
good cork fitting the neck of the flask (or use a
rubber stopper), soften it, and perforate it with
two holes, through one of which the stem of the
funnel passes, and through the other one of the
L-tubes, forming a delivery tube (Fig. 18).
Another form of home-made stopcock funnel
is the following : A funnel tube is cut off short
and connected with a long piece of glass tubing
by means of a bit of rubber tubing which can be closed with a
pinchcock (Fig. 20).
Still another form consists of an ordinary thistle or funnel tube,
into the stem of which fits a bit of rubber tubing slipped over a
glass rod. By pushing the rubber tube into the stem of the funnel
and holding it there by the glass rod, the stopcock is closed.
Fig. 20 HOME-
MADE STOPCOCK
FUNNEL, NO. 2
20
Elementary Chemistry
EXPERIMENT 14. Properties of Oxygen. The first
receiver of gas caught in the three preceding experi-
ments contains the air that was in the generator and is
to be rejected.
Attach a piece of charcoal to a wire, heat it in a
flame until it begins to glow, and then removing the
glass plate from one of the receivers, insert it into the
gas (Fig. 21), replacing the glass plate as far as possible.
The wire may be thrust through a card so that the
charcoal can be supported in the center of the receiver.
Place a little sulfur in a combustion spoon 16 , set it
on fire by directing a flame down upon it, and lower it
into the second receiver.
Put a little red phosphorus
in a combustion spoon, light it
thoroughly and thrust it into the
last receiver. Keep the receiver
covered so that the fumes cannot
escape into the room.
Attach a piece of picture cord
wire to a stiff wire, fray out its
end a little, heat it and dip it into
sulfur so that some may cling to
the wire. Set this on fire and at
once introduce into a jar full of
oxygen. To prevent the intensely
hot oxid of iron which is formed
from breaking the receiver, it
should be a quarter full of water,
or a layer of wet sand may first
be put into the vessel. The object of tipping the frayed
end of the cord with sulfur is to raise the temperature
of the iron to the kindling point so that it too will burn.
What do these experiments teach about combustion in
air and in oxygen ?
Fig. 21 BURNING A SUB-
STANCE IN OXYGEN
Experiments
21
a b c d
Fig. 22 COMBUSTION SPOONS
NOTE 15. Stirring Rods. To make a glass stirring rod, cut
off a piece of solid glass rod of the desired length and round its
ends by holding it in the flame of a Bunsen burner. Stirring rods
may also be made out of tubing by
heating its ends until the glass runs
together and closes them up.
NOTE 16. Combustion Spoons.
Combustion or deflagrating spoons are
little cups to hold combustible materials
to be burned in a receiver of gas.
Besides those procurable at the dealer
in chemical apparatus (Fig. 22 a), ser-
viceable ones may be improvised by (i)
fastening an iron or aluminum thimble
about half full of plaster of Paris (which
has been mixed with water and allowed
to set) to a wire handle (Fig. 22 6) ; (2)
hollowing out a piece of chalk and fastening it to a wire handle
(Fig. 22 c) ; and (3) twisting a wire around a bit of asbestos paper
(Fig. 22 d\
OZONE
EXPERIMENT 15. Preparation of Ozone. Put a
few drops of ether in a small flask and cork it tightly.
The ether will vaporize and a mixture of air and ether
vapor will presently fill up the flask. Heat a stout
glass rod to redness, and plunge it into the mixture of
air and ether vapor. Smell of the product cautiously.
Hold a piece of iodo-starch paper over the mouth of
the flask and note any change of color. Does ether
vapor alone produce any change of color ?
CAUTION. Ether is very inflammable. Do
not have any flames near when pouring it from a
bottle.
EXPERIMENT 16. (Quantitative^ To Find the
Weight of One Liter of Oxygen. Put about 5^-
(i cm - circle) of powdered manganese dioxid in a clean,
dry evaporating dish and heat it as hot as possible for at
least fifteen minutes so as to dry it thoroughly. In the
meantime assemble an apparatus like that shown in
22
Elementary Chemistry
Fig. 23. AB is a nine-inch test tube fitted with a two-
hole rubber stopper. Through one hole passes a short
bit of glass tubing over which a rubber hose provided
with a Hofmann cock or pinchcock is slipped ; through
the other passes an L-tube, the shorter branch of which
fits into the two-hole stopper of an aspirating bottle 17 .
The aspirating bottle, D, is filled full of water, and ,
an " acid bottle, " about half full of
Fig. 23 APPARATUS FOR FINDING THE WEIGHT OF A LITER OF OXYGEN
temperature of the room. Take about 20^- (5 cm -
circle) of dry potassium chlorate and mix it on a piece
of smooth paper with the manganese dioxid, which
should still be warm. Transfer the mixture to the test
tube, which has been previously thoroughly dried, wipe
out any dust that may cling to the upper part of the
tube, and insert just below the stopper a loose plug of
glass wool or a coiled strip of previously ignited asbestos
paper, its object being to prevent the oxygen from car-
rying off any solid particles in passing from the tube.
Experimen ts 23
Weigh the test tube and contents to a centigram as
soon as possible after rilling.
Holding the tube horizontally, tap it gently so as to
make the mixture spread out and lie along the tube,
and connect with the aspirating bottle, the tube being
supported on a ring of a retort stand. Opening the
clips at F and at H (use clip at //), force water into E
by blowing at F, so as to drive all air from the long
rubber tube. Then by suction draw water back into D
until its level reaches nearly to the stopper, raise E so
that the water in D and in E is at the same level, and
close F tightly. Close H and very cautiously remove
the rubber tube from E in such a manner that no water
escapes from the tube. Empty the water out of E and
drain it for a few seconds. Then place the end of the
rubber tube in E and open the clip at H. A little water
will flow out because the level in D is higher than that
in , but there should not be a continual flow, as that
would indicate that the apparatus was leaky.
With a small flame gently heat the test tube, begin-
ning near its mouth. If the mixture begins to froth at
the point heated, heat another portion of it. The flame
must not be held steadily at one place, but played to
and fro through a distance of about 3 cm -. The glass
should not be heated red-hot, as there is then danger of
a hole being blown through it.
When the "acid bottle" is about three-quarters full,
discontinue the heating and let the apparatus stand
until it cools to the temperature of the room. In the
meanwhile read the barometer. Then lift E up or
down (it can be lowered by bringing it down over the
side of the table), hold it so that the level of the water
remains the same for a minute or so in both bottles,
always keeping the end of the rubber tube under
water, and close the cock at H.
Elementary Chemistry
Disconnect the test tube and weigh it again. The
difference between this weight and the one previously
found is the weight of the oxygen evolved.
Remove R without disturbing the water in the
rubber tube, and measure the volume of water it con-
tains by pouring it out into graduated vessels (Appen-
dix BY or by weighing it on a platform balance and
subsequently weighing the empty and drained bottle.
Take the temperature of the water and reduce the
volume of the oxygen to standard conditions. If this
reduced volume be denoted by v and if the weight of
the oxygen be denoted by zv, the weight of a liter may
be computed by means of the pro-
portion :
v : iv :: 1,000 : x
The accepted value for the
weight of a liter of oxygen is 1.43^-.
What possible sources of error can
you point out in the determination
of your value ?
NOTE 17. Aspirators. A large bottle,
Z>, is fitted with a two-hole stopper carry-
ing two L-tubes (Fig. 24). A rubber tube
a little longer than the bottle is slipped
over the outlet tube and may be closed
with a pinchcock, //. To aspirate a gas,
fill the bottle with water, insert the
stopper with its tubes, connect the inlet
tube with the apparatus furnishing the
gas, B ', remove the pinchcock, start the
water flowing so that as it goes out the gas
may be drawn into the bottle. Aspirating
bottles may also be used to store gases ; when the bottle is full of
a gas, slip a bit of rubber tubing over the inlet tube and close it
with a pinchcock, and then close the outlet tube. The gas may
be forced out by connecting the aspirator with a second one filled
with water and placed at a higher level. The water may be made
to siphon over from the second bottle into the first, thus expelling
the gas. The gas may also be driven out at B by connecting the
outlet tube with the water supply of the laboratory.
FlR. 24 ARRANGEMENT OF
TUBES IN AN ASPIRATING
BOTTLE
Experiments
EXPERIMENT 17. (Quantitative^) To Find the Per-
centage of Oxygen in Potassium Chlorate. Clean
and dry a porcelain crucible and cover, place upon
a pipestem triangle
(Fig. 25), and heat
gently at first so as
not to break the cru-
cible, and then as hot
as possible for two or
three minutes. When
the crucible is cool,
weigh it to a centi-
gram (Appendix B}.
Put about 1.5^. (2.
circle) of dry pow-
dered potassium chlo-
rate in the crucible
and weigh again.
Place the covered
crucible on the tri-
angle and heat with a Fi 8- 25 HEATING IN A PORCELAIN CRUCIBLE
flame about 5 cm - high, which just reaches to the bottom
of the crucible. Lift the cover up from time to time
with the forceps and regulate the flame so that the
melted potassium chlorate is seen to give off its oxygen
but slowly. If any should spatter up on the cover,
remove the flame, place the cover bottom side upper-
most on a clean piece of smooth paper, and with a pin
loosen the layer of chlorate and return it to the cruci-
ble, being very careful that none is lost. When the
bubbling is seen to slacken, increase the size of the
flame, and finally heat for ten minutes with a flame
large enough to reach to the top of the crucible when
its yellow spot is just below the bottom of the crucible.
Let cool and weigh,
26 Elementary Chemistry
Again heat very hot for about five minutes, and cool
and weigh as before. If the weight does not change,
pass to the calculations. If the weight is less, heat
again, and continue in this way until two successive
weights are the same. This operation is called heating
to constant weight. The loss of weight is equal to that
of the oxygen. The percentage of oxygen in the
chlorate is calculated thus:
Weight of potass, chlorate : weight of oxygen : : 100 : x
The accepted value for the percentage of oxygen in
potassium chlorate is 39.2. What is the percentage of
error in your result ? Point out any sources of error.
Fig. 26 GAS GENERATOR, PNEUMATIC TROUGH, AND RECEIVERS
HYDROGEN
EXPERIMENT 18. Hydrogen from Acids by Action
of Zinc. Arrange a gas generator as shown in Fig. 26.
A wide-mouthed bottle is fitted with a two-hole stopper
(best of rubber), through which pass a funnel tube 18
and an L-tube. A piece of rubber tubing connects the
L-tube with a second one, thus forming a delivery tube.
Experiments
27
Cover the bottom of the bottle with granulated zinc, fit
in the stopper, push the funnel tube down so that it
nearly touches the bottom of the bottle, and run in
through the funnel tube enough water to just cover, and
thus seal its end. Pour dilute sulfuric or concentrated
hydrochloric acid 19 through the funnel so as to cause a
brisk evolution of gas, and after testing its purity 20 ,
collect four receivers full by water displacement and
pass to Experiment 19.
As an alternate apparatus a stopcock funnel gener-
ator (Fig. 1 8) may be used. Zinc is placed in the bot-
tle, covered with water, and strong hydrochloric acid
dropped in just fast enough to make the gas come off
briskly.
NOTE 18. Funnel Tubes. Funnel tubes are tubes of glass
with one end flared out to form a funnel, or they may be described
as small funnels with long stems. The style shown in Fig. 26 is
sometimes called a " thistle tube," from its fancied resemblance to
the head of a thistle A funnel tube should always have its lower
end dip below the liquid in a generator so as to seal it.
NOTE 19. To Moderate Action of an Acid. If hydrochloric
acid is used and so much is introduced into the generator that
hydrogen is given off too rapidly,
a little water poured through the
funnel will dilute the acid and thus
moderate its action.
CAUTION. Hydrogen mixed
with air is very explosive.
NOTE 20. Testing Hydrogen.
Never perform experiments with
hydrogen until you have convinced
yourself that the hydrogen is free
from air in the following way : Fill
a small test tube with the gas
by water displacement. Place the
thumb over the mouth of the test
tube while it is still under water
and, bringing it close to a flame,
open it so that the gas may pass
into the flame (Fig 27). If the gas
ignites with an almost inaudible report, it is pure ; if with a loud
report, or sharp whistle, it is mixed with air. Continue to gener-
ate the gas until it is pure before collecting it.
Fig. 27 DISCHARGING GAS FROM
A TEST TUBE INTO A FLAME
28
Elementary CJieviistry
EXPERIMENT 19. Properties of Hydrogen. Hold-
ing a receiver full of hydrogen in an inverted position
(Fig. 28), thrust a lighted splinter up into the gas and
then very slowly remove it. Does hydrogen burn ? If
so, what is the appearance of its flame ? Set a receiver
full of hydrogen, with its mouth upward, on the table,
and after waiting at least three minutes, insert a blaz-
ing splinter. How do you account for the result ? What
property of hydrogen
is hereby shown? See
if you can pour hydro-
gen upward. How
can you make sure
that hydrogen is in
the upper receiver?
Pressing a glass
plate or a piece of
cardboard tightly
against the mouth of
a receiver full of hy-
drogen, place it in-
verted upon a receiver
of the same size filled
with air, and slip out
the plate or card (Fig.
14). After at least five
minutes remove the
UDDCT rCCeiVCT and
.
keeping it inverted,
insert a lighted splinter (Fig 28). Account for the result.
What general property of gases is hereby illustrated ?
EXPERIMENT 20. Transpiration of Hydrogen.
Hold down over the delivery tube (a straight tube is
substituted for the L-tube) of a gas generator, from
which hydrogen is issuing rapidly, a dry glass tube,
Fig. 28 - INTRODUCING A LIGHTED SPLINTER
OF WOOD INTO A GAS LIGHTER THAN AIR
Experiments
29
closed at one end with a plug of plaster of Paris, with the
thumb pressed over the plug-. In a few minutes slowly
lift the tube up, keeping it closed
with the thumb all the while, until
it is clear of the delivery tube ;
then dip the open end under water
in a beaker or tumbler and remove
the thumb (Fig. 29). Let the tube
stand for at least fifteen minutes,
examining it from time to time.
Explain what occurs.
EXPERIMENT 21. Combustion
of Hydrogen. Wrap several
folds of a towel over and around
your gas generator so that in case
of an explosion the broken glass
can be prevented from flying
about. Test the purity of the
hydrogen 20 , which should be escaping quite rapidly,
and then attach a straight glass tube drawn out to a
jet 21 to the rubber tube. Ignite the hydrogen and
thrust the jet up into an inverted beaker. What col-
lects in the beaker ?
Pinch the rubber tubing so as to extinguish the
flame, dry the inside of the beaker, and as before
thrust the jet with unlighted hydrogen escaping from
it into the inverted beaker. What occurs ?
NOTE 21. Jet Tubes. To
make a jet tube, select a piece
of glass tubing about i2-
long and ^mm. bore with a
rather thick wall. Heat the
middle in a Bunsen flame,
twirling it so as to heat it uni-
formly. When it begins to
soften, slowly draw it out as shown in Fig. 30. Cut it off at the
narrowest point, and fire-polish the wider ends of the two jet
tubes thus made.
Fig. 2Q APPARATUS FOR
SHOWING TRANSPIRATION OF
A GAS
Fig. 30 STAGES IN MAKING A JET TUBE
3O Elementary Chemistry
EXPERIMENT 22. Oxidation and Reduction. Scrape
a few bits of copper foil or wire bright and clean and
put them into the middle of a glass tube about 30 cm -
long. Heat the tube gently just below the copper, sup-
porting it on a ring stand with interposed wire gauze,
and in a slanting position so that a draft of air may pass
through it. Do not heat the glass to redness. The
blackening of the copper is due to the formation of
copper oxid ; the copper is oxidized.
Fig- 31 PASSING A GAS OVER A SUBSTANCE HEATED IN A TUBE
Let the tube cool and then slipping over one end of
it a delivery tube, and connecting the other end with a
hydrogen generator, pass hydrogen through it (Fig. 31).
After the hydrogen has been found by test to be pure,
heat the copper. What does the change of color go to
show ?
EXPERIMENT 23. Hydrogen from Water by Action
of Sodium. With dry fingers and knife cut off a piece
of sodium not more than 5 mm - in diameter 22 and scrape
it bright and clean. Wrap the bit of sodium up snugly
in a scrap of filter paper which has been moistened in
kerosene 22 , and using tongs bring it under a large test
tube filled with water and inverted in a pneumatic
Experiments
trough. Let go of the sodium so that it may rise into
the tube. If not enough gas is generated to fill the test
tube, use a second piece of sodium. Lift up the tube,
keeping its mouth
down, and bring it to
a flame. How do you
know it contains hy-
drogen ?
NOTE 22. Sodium
Must be Kept Dry. Be
sure that everything that
is used in handling so-
dium is dry. The object
of dipping the paper in
kerosene is to prevent a
too rapid access of the
water to the metal. Too
much paper should not be
used, else the water will
be prevented from com-
ing in contact with the
sodium.
EXPERIMENT 24.
Hydrogen from
Steam by Action of
Magnesium. Draw
out one end of an
L-tube so as to form
a jet 21 and thrust the
other end through a
Cork fitting a Small Fig. 32 HYDROGEN FROM STEAM BY THE
flask (Fig. 32). Put a
little (only a pinch, for if too much is used the heat of
the reaction may be so great as to break the tube)
powdered magnesium in the tube and shake it down so
that it lies along the branch next to the jet. Put a little
water in the flask, insert the cork, and heat the water
to boiling so that a moderate current of steam passes
Elementary Chemistry
Fig. 33 HYDROGEN FROM STEAM BY THE ACTION OP IRON
through the jet. Apply a flame to the issuing- steam
and see if it can be ignited. The little flashes of light
are due to the burning of tiny particles of magnesium,
which are caught up and carried along by the steam.
With a second Bunsen flame heat all the horizontal
branch of the L-tube hot enough to prevent the conden-
sation of moisture in it. Then heat steadily the portion
of the magnesium farthest from the jet until a reaction
begins, and at once remove the flame. Can the gas now
issuing from the flame be set on fire ? Compare with
Experiment 21.
EXPERIMENT 25. Hydrogen from Steam by Action
of Iron. Place enough small brads in a piece of gas-
pipe (or, better, bicycle tubing) 40 cm - to 50^- long and
about 2 cm. bore, to fill the middle of the pipe for a
distance of about 20 cm - f and then fasten the pipe with
wire across a wide ring of a stand (Fig. 33). Attach a
Experiments
33
delivery tube to one end of the pipe and to the other an
L-tube, with a long pieee of rubber tubing, making
connections with a second L-tube inserted in a flask
supported on a second ring above the pipe. Bend a
thick piece of asbestos board into a gable-roof shape
and place it over the pipe. Put a little water in the
flask and arrange the ring supporting it so that it nearly
touches the asbestos. Heat the middle of the gaspipe
as hot as possible, using two burners. Place bits of
wet filter paper over the ends of the pipe and keep
them dripping wet all the time so as to prevent the
charring of the corks. If the water in the flask boils
too vigorously, raise the ring supporting it a little.
Collect some of the gas given off and test it.
EXPERIMENT 26. Hydrogen from Solutions of
Caustic Alkalis by Action of Aluminum. Place a
few bits of aluminum in a test tube and fill it about a
fourth full with caustic soda or potash solution. If effer-
vescence is not very brisk, heat a little. Close the tube
with the thumb, and after a minute or so open it so as to
discharge the gas
into a flame (Fig.
27). Account for
what occurs.
EXPERIMENT
27. Hydrogen
from Sodium
Hydroxid by
Heating with
Iron Powder.
Make an intimate
mixture in a mor-
tar of i g- (6 mm -) of sodium hydroxid and 20^- (4^- circle)
of iron powder, and introduce it into a hard glass test
tube provided with a cork and delivery tube (Fig. 34).
Fig. 34 HEATING A SUBSTANCE IN A TEST TUBE
AND COLLECTING THE GAS EVOLVED
34
Elementary Chemistry
Fig. 35 A COMMON
FORM OF WATER BATH
Supporting" the tube on wire gauze and under a ring,
heat the upper part of the mixture first so as not to
cause too brisk an evolution of the gas,
and collect it by water displacement.
EXPERIMENT 28. Hydrogen from
Calcium Hydroxid (Lime) by Ac-
tion of Iron Powder or Zinc Dust.
Make an intimate mixture of equal
volumes (2 cm - circle) of dry calcium
hydroxid and iron powder, put it into a hard glass test
tube provided with a cork and delivery tube, and heat,
using a test tube holder, collecting the hydrogen
evolved over water. Zinc dust may be used instead of
iron powder in Experi-
ments 27 and 28.
WATER
EXPERIMENT 29. Dis-
solved Matter in Differ-
ent Waters. Slip a small
rubber band over a test
tube about a third of the
way from its closed end,
fill it up to the band with
distilled water, pour the
water thus measured into
a clean evaporating dish
(watch glass or saucer),
and evaporate to dryness
on a water bath 2 3 or sand
bath (asbestos board) 12 .
Note the nature and
Fig. 36 AN IMPROVISED WATER BATH
amount of any residue. Repeat these operations with
hydrant water and other natural waters which may be
available. Compare natures and amounts of residues.
Experiments
35
NOTE 23. Water Baths. To avoid raising the temperature
of a substance above that of boiling water, water baths are used.
A common form (Fig. 35) consists of a copper vessel with a cover
made of a series of rings. By removing one or more of these, a
dish may be set down nearly to its rim on the bath. Water is kept
gently boiling in the bath so that the dish may be surrounded by
steam. Care must be taken to replace from time to time the
water which boils away, else the temperature will be raised too
high. A serviceable water bath may be improvised with a beaker
(best with a lip) and stand (Fig. 36).
EXPERIMENT 30. Distillation. Fit one end of a
long straight tube to a retort or to an L-tube inserted
through the neck of a flask. The other end passes into
a test tube set in a dish of
water. Fill the flask (Fig.
37) or the retort (Fig. 38)
about a third full of water
and add a piece of copper
sulfate (3 >>.). Boil the
water in the flask gently
and collect a test tube full
of the distillate. It is well
to cover the part of the test
tube which is not under water with a piece of filter
paper which is kept wet so as to aid in the condensa-
tion. What is the color of
the distillate ? Can copper
sulfate be totally separated
from water by distillation ?
Fig- 37 SIMPLE DISTILLING APPARA
TUS, FLASK FORM
Fill an evaporating dish
about a fourth full of alco-
hol and set fire to it. While
the alcohol is burning, add Fig 38 _
water in small portions at
a time with constant stirring until the flame goes out.
Clean out the retort or flask, and empty the mixture of
alcohol and water into it. Distill the mixture, collecting
SIMPLE DISTILLING APPARA-
TUS, RETORT FORM
36 Elementary Chemistry
enough of the distillate to fill the test tube about a
fourth full. Pour the distillate into the evaporating
dish and try to set it afire. What does your result prove
about the possibility of separating alcohol and water by
distillation ? Which is the more volatile, water or alco-
hol ? Which has the higher boiling point ?
EXPERIMENT 31. Coagulation Filters. Put a pinch
of clay in a test tube and fill with water. Shake the
water and clay well together and filter (Fig. 10) a por-
tion of the muddy water (a suspension of clay in water).
Is the filtrate clear? Filter the filtrate a second time
and see if it becomes clear. Can clay and water be
separated by filtration ? Now add to the muddy water
a few drops of alum solution, shake up thoroughly, and
filter through a fresh filter. Is the filtrate clear? If
not, add a little more alum and filter again.
EXPERIMENT 32. Conditions Affecting Solution.
(a) fineness of Division. Choose two crystals of po-
tassium dichromate, alum or copper sulfate, both just
small enough to slip into a test tube, and powder one
finely in a mortar. Put the crystal and the powder in
separate test tubes and fill both the tubes about half
full of water. Close the tubes with the thumbs and
shake vigorously. In which case does solution take
place the more rapidly ? In which case is the surface
of contact between the solid and the liquid the larger ?
To save time in dissolving a solid, what preliminary
operation ought it to be subjected to ?
(b) Temperature. Put about 6 - (3 cm - circle) of
powdered potassium dichromate in a test tube, and fill
it about a third full of water. Shake the solid and
liquid well together for some time. Does the solid all
dissolve? Is there a limit to the solubility of a sub-
stance at a given temperature ? Heat to boiling for a
minute or so. Does the solid all dissolve now ? Cool
Experiments 37
the tube and contents by letting cold water run over it.
What happens ? What effect has temperature upon the
solubility of a substance ?
EXPERIMENT 33. (Quantitative^) To Determine
the Solubility of Potassium Dichromate in Water.
Fill a flask (200 to 300 c - c -) a fourth full of powdered
potassium dichromate, and add sufficient water to fill
the flask about three-fourths full. Cork the flask tightly
and place it in a pneumatic trough filled with water at
the temperature of the room. Put a thermometer in the
trough and read its temperature at intervals of about
two minutes, and each time shake well the solid and
liquid in the flask. The temperature should not vary by
more than a degree for at least fifteen minutes. Filter
a portion of the solution thus saturated into a weighed
evaporating dish so as to fill it about half full. Weigh
the evaporating dish and solution and then evaporate
to dryness on a water bath 23 . Be very careful not to
lose any of the solid by spurting. Let the dish and con-
tents cool and again weigh. Calculate the percentage
composition of the solution.
EXPERIMENT 34. (Quantitative.} To Determine the
Solubility of Air in Water. Shake a large bottle filled
about half full of water vigorously for several minutes so
as to saturate it thoroughly with air. The water should
be at the temperature of the room, and care should be
taken not to warm it up in shaking by the heat of the
hands. Fit a small flask (200 to 300 c - c -} with a stopper
(best of rubber) and a delivery tube of narrow bore (not
more than 2 mm -) of the form shown in Fig. 39. Set the
flask on a ring of a stand with interposed wire gauze so
that its delivery tube may come under a test tube placed
in a beaker set on a second ring of the same stand. Fill
both the beaker and the test tube with water, invert the
filled test tube in the beaker, and pour out as much
Elementary Chemistry
water as possible from the beaker without the water in
the test tube escaping. Take the temperature of the
water in the bottle and fill the flask brimful. Then
insert the stopper so
that the delivery tube
will be filled with
water also. There
must not be any bub-
bles of air either in the
flask or the delivery
tube.
Weigh the flask,
delivery tube, and con-
tents to decigrams, set
the flask upon the wire
gauze so that its deliv-
ery tube engages un-
der the test tube, and
heat with a small
flame, making the
water boil vigorously
until a cracking sound
is heard, indicating
that all the air has
been expelled from
the water. Remove the delivery tube from the water
in the beaker and stop heating. Fill the beaker with
water at the temperature of the room, lift the test tube
up so that the level of the water inside and outside is
the same, and mark it with a small level rubber band
slipped over the test tube. Remove the test tube and
determine the volume of the air driven out of the water
either with a burette (Appendix B) or by weighing the
water which fills the tube up to the rubber band. Dry
flask and delivery tube and weigh. Record results thus:
Fig. 39 APPARATUS FOR DETERMINING THE
SOLUBILITY OF AIR IN WATER
Experiments
39
Weight of water filling flask and delivery tube = A <?"
Volume of air expelled at and mm. of mercury B c.c.
Volume of air reduced to o and 760 mm. of mercury = C c.c.
No. of c.c. of air at o and 760 mm - dissolved by A c.c. of water.
No. of c.c. of air dissolved by 1,000 c.c. of \vaterat = DC.C.
Accepted value for solubility of air in water (Appendix C).
EXPERIMENT 35. Heat Effects of Solution. Have
ready at hand 5.0^- of the solids named in the table
below in the form of a fine, dry powder. Measure.
(Appendix B) io.o c - c - of water at the temperature of
the room into a test tube, insert a thermometer, stir,
and read the temperature. Add all at once the first of
the powders, stir well with the thermometer, holding
the test tube with a holder so as not to warm the solu-
tion with the hand, and record the highest temperature
attained. Repeat these operations with the other sol-
ids, cleaning out the test tube after each trial.
Add 5.0^- of alcohol to ic-.o^- of water and find the
temperature of the well-stirred mixture. Also add
5.0^- of strong sulfuric acid to io.o c - c - of water and take
the maximum temperature. Record results as follows :
HEAT EFFECTS OF SOLUTION
SUBSTANCES
Solvent
Temperature
Change of
Tem-
perature
Name
Amt.
Name
Amt.
Initial
Highest
or
Lowest
Maxi-
mum
Kind
Ammonium chlorid..
Calcium chlorid
Ammonium nitrate .
Potassium nitrate
Copper sulfate (dehy-
drated) _ .
Sugar
Potassium carbonate.
Sodium carbonate
Alcohol
Sulfuric acid
40 Elementary Chemistry
EXPERIMENT 36. Supersaturation. Fill a test tube
about a fourth full of sodium acetate (or sodium sul-
fate) crystals and add barely enough water to cover
them. Heat cautiously to boiling until a clear solution
results and boil vigorously for a minute or so. Set the
tube aside in a slanting position so that any dust may
fall on the sides of the tube and not reach the solution.
After the solution is cool drop into it a very small frag-
ment of a sodium acetate (sodium sulfate) crystal and
shake the tube. What happens ?
EXPERIMENT 37. Water of Crystallization. Place
in separate clean and dry small test tubes a few small
crystals of potassium nitrate, copper sulfate, and cobalt
chlorid. Place the test tubes on the wire gauze and
place under them a frame made of iron wire fashioned
so that while their closed ends converge to a common
center, their mouths just project beyond the gauze and
are lower than their closed ends. Adjust the flame of
a Bunsen burner so that it keeps red hot a small circle
just below the closed ends of the test tubes, being care-
ful not to let the flame strike through the gauze. Note
carefully the appearance of moisture in the mouths of
the tubes. In which case is it the most abundant ?
What changes do the substances undergo ? Which of
them contain water of crystallization and which me-
chanically enclosed water ? When the water of crystal-
lization is expelled from a substance, the substance is
said to be dehydrated.
Using a dilute solution of cobalt chlorid instead of
ink, write on paper with a clean, new pen. Is the writ-
ing almost invisible ? Waft the paper over a flame so
as to \varm it. Do the characters now show and in what
color? Breathe upon the writing. What happens?
How do you explain the action of this kind of sympa-
thetic ink ?
Experiments 41
EXPERIMENT 38. (Quantitative.} To Find the
Percentage of Water of Crystallization in Gypsum.
Clean and weigh to centigrams a porcelain crucible
and cover. Place in it enough gypsum in powder or
coarse fragments to fill it about a fourth full. Weigh,
place it upon a pipestem triangle (Fig. 25), and heat
with a small flame for about ten minutes. Let the
crucible cool and weigh it. Heat the crucible once more
for about five minutes, let cool and weigh. If it has
lost in weight, heat it still again, and so on to constant
weight. Calculate the percentage of water of crystalli-
zation contained in gypsum.
Instead of a crucible, test tubes or clay pipes may be
used. A test tube is weighed, filled about a sixth full
of gypsum, again weighed and heated (held in a test
tube holder in a slanting position) to constant weight.
EXPERIMENT 39. Deliquescence. Put a little solid
potassium hydroxid ($ mm -) in an evaporating dish or
watch glass, set it aside in a safe place, and examine it
after a few hours. Review Experiment 7. How do
you account for the change ?
EXPERIMENT 40. Efflorescence. Choose a clear
crystal of sodium sulfate, place it upon a watch glass or
evaporating dish, set it aside in a safe place, and examine
it from time to time. (It is advisable to weigh the dish
and crystal so as to keep track of any change in weight.)
What change does the crystal undergo ?
EXPERIMENT 41. Test for Water. Expel the water
of crystallization from a little copper sulfate by heating
it in an evaporating dish or a tin-box cover. Place a
little of the dehydrated substance on a watch glass and
add a drop of strong alcohol. Does the substance turn
blue ? Try carbon bisulfid, ether, kerosene, or any other
liquids not containing water which are available.
Finally try water. How is the result a test for water?
42 Elementary Chemistry
EXPERIMENT 42. (Quantitative.) To Ascertain the
Volumetric Composition of Water. Choose two long
and narrow test tubes as nearly of the same size as
possible, and slip over them narrow rubber bands or
tie around them bits of cotton string to serve as
markers. Place one marker about one- third of the
length of one of the tubes from its open end, and the
other marker on the second test tube about one-fourth
of the length of the tube from the open end. Fill
both tubes with water and, holding them in a pneumatic
trough, let in air until the level of the water inside and
outside is at the markers. Have a hydrogen generator
conveniently at hand from which hydrogen is issuing at
the rate of about two bubbles a second. Thrust one of
the test tubes over the delivery tube, and the instant
it is filled with hydrogen remove it and set it aside in
the pneumatic trough with its end under water. Do
likewise with the other tube. These tubes contain
definite, measurable volumes of air and hydrogen.
Now a mixture of air and hydrogen which contains
the two gases in just the right proportions totally to
combine and form water, explodes, when ignited, with
a sharp, whistling sound ; otherwise, if the proportions
are not just right, the sound of the explosion is fuller
and louder. Close the two tubes with the thumbs
under water and, bringing them on either side of a
flame (Fig. 27), let their contents pass into the flame in
rapid succession and note the character of the sounds.
There will probably be an easily detectable difference.
Now push the marker of the test tube which con-
tained the greater volume of hydrogen down a little
(a couple of millimeters), and the other marker up
about the same distance, thus making the volumes
more nearly equal. Fill them with air and with hydro-
gen as before, and ignite their contents. Continue in
Experiments 43
this way until you can detect but a slight difference, if
any, in the sound of the explosions, which should be
more like a whistle than a report.
Empty out the tubes and drain them. Ascertain the
volume up to the marker, either by running- in water
from a burette or by weighing. (Appendix B.) Fill
the tubes brimming full with measured amounts of
water, thus finding the volumes of the mixtures of air
and hydrogen, whence by subtraction the volume of the
hydrogen may be ascertained. As air contains very
nearly one-fifth of oxygen by volume, one-fifth of the
volume up to the marker will be the oxygen which has
combined with the hydrogen. Enter results thus :
First Second
test tube. test tube.
Volume of air = A' c.c. ~ A c.c.
Volume of oxygen ( of A) = B' c.c. B c.c.
Volume of hydrogen = C' c.c. C c.c.
(B-j-B')^- of oxygen combine with (C -f- C') c - c -
of hydrogen, whence i c - c - of oxygen combines with
(C + C')/( B + B')^- of hydrogen. The accepted ratio
is i : 2. What are the sources of error?
HYDROGEN DIOXID
EXPERIMENT 43. Hydrogen Dioxid by Action of
Sodium Peroxid on Water. Add a dozen or so drops
of strong sulfuric acid to about 50^- of cold water in a
beaker and stir well. Cool the solution as much as pos-
sible (if ice is available, put a few pieces in the solution)
and add in small portions with constant stirring about 2#-
( i cm. circle) of sodium peroxid. Pass to Experiment 45.
EXPERIMENT 44. Hydrogen Dioxid by Action of
Sulfuric Acid on Barium Dioxid. Put about io#-
(4 cm. circle) of barium dioxid in a beaker, and moisten
it with a few drops of water. Add about 30 c - c - of cold,
44 Elementary Chemistry
dilute (about 10 per cent) sulfuric acid, stir well for sev-
eral minutes, let the solid settle, and decant the solution
of hydrogen dioxid from the insoluble barium sulfate.
If the filtrate is not clear, pour it upon the same filter
paper and continue in this way until it is perfectly clear.
Pass to Experiment 45.
EXPERIMENT 45. Properties of Hydrogen Dioxid.
Action of Potassium Permanganate Solution. Fill a test
tube about a fourth full of the hydrogen dioxid solution
prepared in Experiments 43 or 44, add a drop or so of
potassium permanganate solution and shake well. The
gas evolved is oxygen. Continue adding the perman-
ganate until the color is not discharged.
Action on lodo-Starcli Paper. Moisten iodo-starch
paper with a solution of hydrogen dioxid. What effect?
Where else has this paper been used ? W'hat two sub-
stances is it a test for ? How may they be distinguished
from each other ?
Action on Potassium DicJiromate Solution. Fill a
large test tube nearly full of water and add just enough
potassium dichromate solution to tinge it a very light
yellow. Now add a couple of drops of sulfuric acid,
and then a dozen or so drops of hydrogen peroxid solu-
tion. Shake well and note what happens. Pour some
out into a dish and let it stand for a few minutes. Fill
a small test tube about a sixth full of hydrogen dioxid
solution and add enough ether to form a layer about
half a centimeter thick.
CAUTION. Do not have any flames near when
using ether.
On shaking, do the two liquids mix ? Add one drop
of potassium dichromate solution and shake gently.
Result ? If you are in doubt about the result add
another drop, but do not use too much potassium
dichromate solution.
Experimen ts 45
EXPERIMENT 46. (Quantitative.} To Verify the
Law of Definite Proportions by Weight. Weigh
out exactly 2.00 of sodium carbonate (washing soda)
in a porcelain evaporating dish. Add concentrated
hydrochloric acid, a few drops at a time, being careful
to avoid any loss from the effervescence. When the
sodium carbonate is wholly dissolved, evaporate to dry-
ness (Fig. 9) and constant weight. The residue is com-
mon salt.
Repeat, using exactly 4.00 *" of sodium carbonate.
Calculate the ratio of the sodium carbonate to the salt
in both cases. How do they compare ? How is this a
proof of the law in question ?
EXPERIMENT 47. ( Quantitative} To Verify the Law
of Definite Proportions by Volume, (a) Put about
25 c.c. of concentrated hydrochloric acid in a beaker and
mix with it about an equal volume of water. Fill a
burette (Appendix B) with this mixture. Also fill a
second burette with concentrated ammonium hydroxid.
(b) Run 5.0 c - c - of the acid into a weighed evap-
orating dish and add a couple of drops of litmus
solution. After reading the burette containing the
ammonium hydroxid, run the ammonium hydroxid
into the acid slowly with constant stirring until the red
color just changes to blue.
The acid and ammonium hydroxid combine to form
a solid ammonium chlorid. Evaporate to constant
weight on a water bath.
(c) Put the same volume of acid into a second
weighed evaporating dish and add twice as much ammo-
nium hydroxid as before. Evaporate to constant weight
on a water bath.
(d) Run i o.o c - c - of the acid into a third weighed dish
and cautiously add just enough ammonium hydroxid to
change the color. Evaporate to constant weight.
46
Elementary Chemistry
(e) Put a few drops of hydrochloric acid in a dish
and evaporate to dryness. Is there any residue ? Does
ammonium hydroxid leave a residue when evaporated ?
Try it with a few
drops.
(f) Compare the
weights of ammo-
nium chlorid obtained
in (/;), (c), (d). How
do your results verify
the law under discus-
sion ?
EXPERIMENT 48.
(Quantitative.) To
Verify the Law of
Multiple Propor-
tions. Arrange an
apparatus as shown in
Fig. 40. The cylinder should be of at least 500 c - c - capac-
ity. Weigh out exactly 2.00^- and also 4.00 & of baking
soda (Appendix B). Put the larger amount in an evap-
orating dish and heat as hot as possible for at least ten
minutes. While the heating is going on, put the smaller
portion into the generator and pour IQC-C. O f hydrochloric
acid into the stopcock funnel. Fill the cylinder with
water and invert it in the pneumatic trough. Run the
acid into the generator and collect the carbonic acid gas
given off. Be careful not to let any of the gas escape
through the stopcock. When no more gas is evolved,
remove and clean the generator thoroughly. Mark the
level of the water inside the cylinder with a rubber band.
Now put the portion which has been heated into
the generator ; fill the cylinder afresh with water, and
collect the gas given off when 10 c - c - of hydrochloric acid
are run in upon the soda.
Fig. 40 STOPCOCK FUNNEL GAS GENERATOR
AND CYLINDER USED IN ILLUSTRATING THE LAW
OF MULTIPLE PROPORTIONS
Experiments
47
Are the volumes of gas in the two cases approxi-
mately the same? Has the effect of the heating been
to expel half of the carbonic acid gas contained in the
baking soda? By heating, the baking soda has been
converted into washing soda. How much greater a
volume of carbonic acid does baking soda contain than
does washing soda? How do your results verify the
law in question ?
NITROGEN AND ITS HYDROGEN COMPOUNDS
EXPERIMENT 49. Separation of Nitrogen from
the Air. Bend the wire of a combustion spoon as
show r n in Fig. 41, and fill the cup with red phosphorus.
Ignite the phos-
phorus by direct-
ing a Bunsen flame
down upon it, and,
resting the bend
of the wire on the
bottom of the
pneumatic trough,
press a large, wide-
mouthed bottle
over it.
Note carefully
how the phos-
phorus burns.
What makes it
finally go out?
What becomes of
the white smoke
at first formed ?
What makes the water rise in the receiver? Let the
apparatus stand until the fumes have completely dis-
appeared. Then estimate the ratio of the volume of
Fig. 41 APPARATUS FOR REMOVING THE OXYGEN
FROM A CONFINED PORTION OF AIR
48 Elementary Chemistry
the air taken to the volume of the gas left. Close the
receiver with a glass plate and set it upright upon the
table. Move the plate just far enough to one side to
permit the entrance of a blazing splinter of wood.
Does it continue to burn ? Is nitrogen combustible ?
Is it a supporter of combustion ?
EXPERIMENT 50. Nitrogen by the Decomposition
of Ammonium Nitrite. 24 Mix in a mortar about 10^-
(6 cm - circle) of ammonium chlorid with about i$ff- of
sodium nitrite and place the mixture in a flask provided
with a perforated stopper and delivery tube (Fig. 16).
Just cover the mixture with water and heat gently
with interposed wire gauze until the reaction begins ;
then remove the flame. Collect two receivers full by
water displacement. If the liquid effervesces too much,
cool it by pouring water over the flask. Reject the
first bottle full, as it contains the air which was in the
apparatus. Remove the second receiver after closing it
with a glass slip and, holding it upside down (Why ?),
thrust a lighted splinter up into the gas. Is nitrogen a
supporter of combustion ? Does it burn ?
NOTE 24. Ammonium Nitrite Does Not Keep Well. Hence
it is made in this experiment by the reaction between ammonium
chlorid and sodium nitrite. The heat caused by the reaction is
usually sufficient to decompose the ammonium nitrite into water
and nitrogen as soon as it is formed.
EXPERIMENT 51. Nitrogen from Potassium Ni-
trate by Action of Iron Powder. Mix well io^- ($cm.
circle) of iron powder with 0.5 & (2 cm - circle) of pow-
dered potassium nitrate, put the mixture in a hard glass
test tube, fitted with a cork and delivery tube (Fig. 34),
and apply heat. Be careful to heat very gradually, as
the reaction may become rather violent. Collect sam-
ples of the gas by water displacement, and test them
with a blazing splinter.
Experiments 49
EXPERIMENT 52. Ammonia from Ammonium Salts
by Action of Caustic Alkalis or Lime. Cover a pinch
of ammonium chlorid or nitrate in a test tube with po-
tassium or sodium hydroxid (caustic potash or soda)
solution. Heat gently to boiling and cautiously observe
odor by wafting the air above the mouth of the test
tube against the nostrils. Put a strip of moistened pink
litmus paper 25 across the mouth of the test tube and
note any change of color.
Put a little slaked lime 2 6 in the palm of one hand and
a little ammonium chlorid or nitrate in the other. Smell
of each substance. Then rub the substances together
between the palms and smell again. Also touch the
mixture with a strip of moist pink litmus paper 25 .
NOTE 25. Pink Litmus Paper. To make litmus paper of a
pink color, put a few drops of dilute hydrochloric acid in a watch
glass or on a piece of glass, and draw the strip of paper through
it. Wash out the excess of the acid by holding the paper in a
stream of water from the hydrant. The blue color may be restored
by using ammonium hydroxid instead of hydrochloric acid. As
litmus paper is usually sold with its color intermediate between
Eink and blue, it is a good practice to treat it as above so as to
ave it of a decided blue or pink color before making a test.
NOTE 26. Use Freshly Slaked Lime. The lime must be
freshly slaked. "Air-slaked " lime generally will not do.
EXPERIMENT 53. Ammonia from the Destructive
Distillation of Some Animal Substances. Heat some
such substance as gelatin, glue, hair, or feathers in a
test tube with a moistened strip of pink litmus paper
held across its mouth. What products, solid, liquid,
and gaseous, are formed ?
EXPERIMENT 54. Preparation and Properties of
Ammonia. Arrange an apparatus as shown in Fig. 42.
Put about 25 # (ycm. circle) ammonium chlorid and
about three times its bulk of slaked lime 26 in the
flask, and add just enough water to make a pasty mass ;
or, fill the flask about a third full of strong ammonia
elementary Chemistry
Fig. 42 APPARATUS FOR PREPARING AMMONIA
water (ammonium hydroxid). The rim of the funnel
should dip just below the surface of the water in the
dish. Heat very gently, and as soon as the gas evolved
is nearly all absorbed by the water, substitute for the
funnel a straight glass tube. Insert this delivery tube
into a narrow-mouthed bottle and collect the bottle full
of the gas by upward displacement 27 .
Keeping the receiver always upside down (Why?),
cork it tightly (or cover it with a greased glass plate) and
set it aside in an inverted position. Collect in like man-
ner a second bottle full of the gas. Dip a glass rod into
strong hydrochloric acid and bring the adherent drop
just above the jet of gas. What occurs ? Replace the fun-
nel and continue to absorb the gas as long as it can be
made to come off. The solution is ammonium hydroxid.
Hold the neck of the first receiver under water and
remove the cork. Does it seem to stick in the neck ?
If so, why ? What makes the water rush up into the
bottle ? Test the water in the bottle with pink litmus
Experiments 5 1
paper 25 . Hold the second receiver upside down, re-
move the cork and insert a lighted splinter of wood.
Does ammonia support combustion ? Does it burn ?
To a little of the ammonium hydroxid add a few
drops of Nessler's reagent. Also test a little with solu-
tions of iron chlorid, ferrous sulfate, aluminum chlorid
or sulfate, and copper sulfate (at first very little, and
then an excess). Put a little ammonium hydroxid in a
small test tube and boil for a few seconds so as to fill
the tube with ammonia. Then rapidly invert it in a
beaker filled with very dilute copper sulfate solution.
What happens, especially in change of color ?
NOTE 27. Collecting a Gas by Upward Displacement. When
a gas is soluble in water it cannot of course be collected by water
displacement. If the gas is lighter than air, it can be collected by
delivering it into an inverted receiver ; the delivery tube should
be thrust as high up as possible, so that the lighter gas may push
the air down and out of the receiver.
EXPERIMENT 55. Ammonia by the Interaction of
Potassium Nitrate, Potassium Hydroxid, and Iron
Powder. Mix together 0.5^- (2 cm - circle) of potassium
nitrate, 0.3^- (6 mm - circle) of potassium hydroxid, and 25^-
(5 cm. circle) of iron powder, put the mixture in a hard
glass test tube and heat gently. How can you prove
that ammonia is given off ? What is the gaseous product
of heating a mixture of potassium nitrate and iron pow-
der (Experiment 51)? What of heating a mixture of
potassium hydroxid and aluminum powder (Experiment
26) ? Zinc or aluminum powder would also answer.
CARBON
EXPERIMENT 56. Formation of Charcoal. Place in
a small Hessian crucible or tin- box cover a thin layer
of sand and place upon it a small piece of soft wood
and of hard wood, a fragment of bone, and a lump of
starch. Cover them with a thick layer of sand and
Elementary Chemistry
heat very hot for at least twenty minutes. Pour off the
sand and compare the products. What conclusions can
you draw as to the distribution of carbon ? What was
the purpose of imbedding the objects in sand ?
EXPERIMENT 57. Graphite from Pig Iron. Put
about 3^- (2 cm - circle) of borings of foundry pig iron in a
beaker and add ioo c - c -
of dilute nitric acid
(made by mixing io c - c -
of the concentrated
acid with go c - c - of
water). Boil gently
(Fig. 43), replacing
from time to time
the water which has
boiled away, until the
residue does not seem
gritty when rubbed
with a glass rod. Fil-
ter and wash the resi-
due and let it dry.
Compare its proper-
ties with those of sam-
ples of graphite that
you can obtain from
different sources.
EXPERIMENT 58. Preparation of Lampblack. Put
a lump (2 mm,} of rosin in a spoon or tin-box cover and
set fire to it. Hold the rounded end of a test tube filled
with cold water in the flame. Examine the deposit on
the tube. Why was the tube filled with cold water?
EXPERIMENT 59. Density and Porosity of Char-
coal. Put a piece of charcoal in a test tube half full
of water. Does the charcoal seem lighter or heavier
than water ? Boil the water for several minutes. What
Fig. 43 BOILING A LIQUID IN A BEAKER
Experiments 5 3
is observed on the surface of the charcoal ? Let the
water cool with the charcoal in it, and look at it from
time to time. What is your final conclusion as to the
density of charcoal ? Do not draw this conclusion until
the charcoal has been in the water for some time.
Account for its behavior before and after boiling.
With the aid of tongs hold a piece of charcoal in a
Bunsen flame until it is red hot, and then drop it into
water. Wait until it sinks. Explain its sinking.
EXPERIMENT 60. Adsorption of Gases by Char-
coal. Fill a large test tube half full of w r ater and add
to it, drop by drop, ammonium hydroxid, so as to give
it a faintly perceptible smell. You should just be able
to smell the ammonia when, after shaking up the liquid,
the mouth of the test tube is put under the nostrils.
Heat some finely powdered charcoal in an evaporating
dish nearly to redness, let it cool, and pour it into the
weak ammonia water. Shake well for a minute or so,
and then apply the tube to the nostrils. Has the smell
of ammonia been diminished ? What was the purpose
of heating the charcoal beforehand ?
EXPERIMENT 61. Reduction by Charcoal. Put a
pinch of finely powdered charcoal in a small test tube,
a pinch of powdered copper oxid in a second test tube,
and a few bits of copper wire or granulated copper in
a third tube. Fill each tube about a fifth full of dilute
nitric acid and shake well. Note any action that may
take place, such as effervescence, colored fumes or liquid.
Place the test tubes side by side in a beaker about
half full of water, and heat the water until it is so hot
that you can hardly bear your hand in it. Note now
any changes or reactions in the test tubes. Are the
differences in the behavior of the three solids when
placed in nitric acid sufficient to characterize them ?
In other words, is this "nitric acid test" decisive?
54 Elementary Chemistry
Mix well in a mortar 4^- ($ cm ' circle) of copper oxid
with 2ff- (4 cm - circle) of powdered charcoal. Place the
mixture in a test tube and heat as hot as possible with-
out melting the glass for at least five minutes. Does
the color of the mixture change ? If so, what substance
may it indicate the presence of ? Put a pinch of the
product in a small test tube and add nitric acid as above.
Is there any evidence that copper has been formed and
is present? What role does the charcoal play?
EXPERIMENT 62. Decolorizing Action of Bone-
black. Into a test tube nearly full of water put enough
molasses or litmus solution to tinge the water slightly.
Fit a funnel with a filter paper and nearly fill it with
boneblack. Pour the mixture prepared upon the bone-
black and catch the filtrate in a second test tube. If
the filtrate is not perfectly colorless, pour it upon the
boneblack again, and continue this until all the color is
removed from the mixture.
EXPERIMENT 63. Combustibility of Different
Forms of Carbon. Place a wire gauze on a ring of a
stand at such a height above a Bunsen flame that a
circle about 3 cm - in diameter is made red hot. Place in
this circle pieces "($ mm -) of graphite (from a "lead pen-
cil "), of charcoal, of gas carbon, of soft and of hard coal,
and heat until the charcoal changes into ash ; be care-
ful to have all the substances equally heated. Describe
fully the changes which each substance undergoes.
THE COMPOUNDS OF CARBON WITH OXYGEN
EXPERIMENT 64. Carbon Dioxid a Product of Com-
bustion. Drop a piece of burning paper into a dry, wide-
mouthed bottle and cover it with a glass slip. When the
paper ceases to burn, pour in some lime water and shake
the contents of the bottle vigorously. What happens
to the lime water ?
Experiments
55
EXPERIMENT 65. Carbon Dioxid Given off in Res-
piration. Fill a large test tube a third full of lime water,
and by means of a glass tube make the breath bubble
through the solution a dozen or so times. What occurs ?
EXPERIMENT 66. Carbon Dioxid Produced by
Fermentation. Dissolve a handful of brown sugar or
an equal bulk of molasses in about a liter of water con-
tained in a bottle or flask provided with a delivery
tube. Add a little yeast and set the apparatus in a
warm place (30 to 40). Collect the gas which soon
begins to form in test tubes and test it with lime water.
Fig. 44 GENERATING A GAS AND COLLECTING IT BY DOWNWARD DISPLACEMENT
EXPERIMENT 67. Carbon Dioxid from a Carbonate
by Action of an Acid. Place several lumps of marble
(calcium carbonate) in a gas generator and cover them
with water. Connect with a wash bottle a fourth full
of water (Fig. 44). Pour some strong hydrochloric acid
down the funnel so as to cause a brisk evolution of gas.
Collect the gas by placing the delivery tube at the
56 Elementary C lie mist ry
bottom of a receiver. Carbon dioxid is heavier than
air and collects at the bottom of the receiver. This
method of collecting a gas is known as that of "down-
ward displacement." Collect five receivers full for use
in Experiment 68, and close them with glass slips.
EXPERIMENT 68. Properties of Carbon Dioxid.
Lower a lighted splinter of wood into a receiver of car-
bon dioxid. What happens ? Pour a little lime water
into another receiver of the gas and shake it up. What
happens ? Pour a receiver full of carbon dioxid as you
would a receiver of water into a second receiver con-
taining only air. Lower a lighted splinter into the
second receiver. What evidence is there that the gas
has been poured from the one receiver into the other ?
Empty just as if the carbon dioxid were water a receiver
full of carbon dioxid upon a candle flame. What hap-
pens ? Holding one end of a bit of magnesium ribbon
by means of tongs, ignite the other end thoroughly,
and plunge it into a large receiver full of the gas.
What are the black and the white particles formed ?
EXPERIMENT 69. Action of Carbon Dioxid on
Litmus. Add a few drops of litmus solution to water
in a test tube and pass carbon dioxid into it for a few
minutes. What change of color ?
EXPERIMENT 70. Carbon Dioxid Absorbed by
Sodium or Potassium Hydroxid Solutions. Pass
carbon dioxid into a solution of caustic potash or soda
(potassium or sodium hydroxid solution). When the
gas ceases to be absorbed, pour a little of the solution
into a test tube and add dilute hydrochloric acid. What
does the effervescence that ensues go to show ? Pour
the rest of the solution into a shallow dish and let it
stand until crystals appear. Place some of these crys-
tals in a test tube and add hydrochloric acid. What evi-
dence is there that the crystalline mass is a carbonate?
Experiments
57
EXPERIMENT 71. Carbon Dioxid in Solution Dis-
solves Calcium Carbonate. Mix lime water with an
equal volume of water in a test tube and pass carbon
dioxid, purified by passing it through water in a wash
bottle (Fig. 44), through it for some time. Does the
white precipitate of calcium carbonate finally dissolve.?
Boil some of this clear solution so as to expel the car-
bon dioxid from solution. What happens ?
EXPERIMENT 72. Carbon Monoxid by Action of
Sulfuric Acid on Sodium Formate. Fit a test tube
with a perforated cork through
which passes a short, straight
piece of glass tubing ending
in a jet (Fig. 45). Put enough
sodium formate in the tube
to fill it to the depth of about
a centimeter, and cover it to
a depth of about 4 cm - with
strong sulfuric acid. Hold-
ing the tube with a test tube
holder, warm it cautiously so
that the contents may not
froth over, and light the gas
given off. What is the appear-
ance of the flame just as soon
as the gas is lighted and be-
fore the glass tip has been Fig. 45- PREPARING CARBON MON-
heated red hot? Be very
careful not to let the poisonous gas escape into the
room, repeatedly applying a light to the jet tube so as
to burn the gas as soon as formed.
P^XPERIMENT 73. Carbon Monoxid by the Action of
Sulfuric Acid on Potassium Ferrocyanid. Put about
io-- (5 cm. circle) of potassium ferrocyanid in a flask (200
to 300 c-c-) provided with a delivery tube ending in a jet,
Elementary Chemistry
and add about 50^- of strong sulfuric acid. Heat
gently (Fig. 46) and ignite the escaping gas ; note the
appearance of the flame and any other phenomena that
you may observe.
EXPERIMENT 74. Oxids of
Carbon from Oxalic Acid.
Into a flask (200 to 300 c - c -)
fitted with a delivery tube put
about 5^- (4- circle) of solid
oxalic acid and add about
40^- of strong sulfuric acid.
Heat cautiously and after the
air has all been Driven out of
the apparatus, collect by water
displacement a long, narrow
test tube full of the gas. Close
the tube with the thumb un-
der water and transfer it to a
beaker nearly full of a very
dilute solution of caustic soda
or potash. Let it stand until
the liquid ceases to rise in the tube. What is the decrease
in volume due to ? What is the ratio of the volume of
the two oxids of carbon obtained from oxalic acid ?
EXPERIMENT 75. (Quantitative.) To Find the
Weight of a Liter of Carbon Dioxid. Fit a flask
(300 to 400 c - c -) with a one-hole rubber stopper through
which passes a glass tube a little longer than the flask,
over one end of which is slipped a bit of rubber tubing
(Fig. 47). Fill the flask brimming full of cold water,
and insert the stopper and tube; be careful to exclude
all air bubbles and to have the water reach to the end
of the rubber tip. Close the rubber tube as near to the
glass as possible with a pinchcock, and mark with a
pencil a line around the stopper even with the rim of
Fig. 46 PREPARING CARBON MON-
OXID FROM POTASSIUM FERROCY-
ANID
Experiments
59
the flask's neck. Weigh to decigrams the flask thus
filled with water ; this weight in grams is equal to the
volume in cubic centimeters.
Empty out the water and dry the apparatus thor-
oughly. Multiply the volume by 0.001293 (the weight
of i c - c - of air at standard conditions) to get the weight
of air filling the flask at standard conditions. Open the
pinchcock and connect the rubber tubing with a cur-
rent of dry carbon dioxid. Loosen the stopper so that
the carbon dioxid delivered at the bottom of the flask
can drive out the air. After about five minutes insert
the stopper to the same extent as before, i. c., to the
pencil line, close the pinchcock, and disconnect from
the carbon dioxid generator. Open the pinchcock for
an instant so as to let the ex-
cess of carbon dioxid escape,
and weigh the apparatus to
centigrams. Read the ther-
mometer and the barometer.
Repeat the operation of
filling the flask with carbon
dioxid so as to make sure that
all the air has been expelled ;
this will be shown by no in-
crease in weight in the second
weighing. As soon as a con-
stant weight has been attained,
again read the thermometer
and barometer, using the last
readings for the calculations.
The difference of the weights
of the flask full of air and filled with carbon dioxid, plus
the calculated weight of the air, gives the weight of the
carbon dioxid. Reduce this volume to o and j6o mm -,
and then compute the weight of a liter of carbon dioxid.
Fig. 47 APPARATUS FOR FINDING
THE WEIGHT OF A LITER OF CARBON
DIOXID
6o
Elementary Chemistry
SOME NITROGEN AND HYDROGEN COMPOUNDS
OF CARBON
EXPERIMENT 76. Methane from Sodium Acetate
by Action of Soda-lime. Pulverize about 10^- of fused
and dry sodium acetate and mix it thoroughly in a mortar
with an equal weight of fused and dry soda-lime. Heat
the mixture in a
flask ( 100 to 2oo c - c -)
provided with a
one-hole cork, de-
livery tube and a
safety bottle 28
(Fig. 48), and col-
lect a couple of
receivers full by
water displace-
ment. Ascertain
whether the gas is
combustible or a
supporter of com-
bustion. Pour a little lime water into one of the
receivers just after the methane has been ignited. The
result proves what element to be present in methane ?
How could you prove the presence of hydrogen in it ?
EXPERIMENT 77. Ethylene from Alcohol by Ac-
tion of Sulfuric Acid. Pour 10^- of water into a
flask (200 to 3oo c -< ; -), add slowly with constant stirring
30 c - c - of strong sulfuric acid, and cool the flask by hold-
ing it under cold water. Then add io c - c - of alcohol. Fit
a cork and delivery tube to the flask, interpose a safety
bottle 28 (Fig. 48), heat gently, and collect a couple of
receivers full of the gas by water displacement. Note
its odor. How does it burn ? Compare its flame with
those of the other combustible gases thus far studied.
Fig. 48 APPARATUS FOR GENERATING A GAS TO
COLLECTED BY WATER DISPLACEMENT
Experiments 61
NOTE 28. Safety Bottle. The object of the safety bottle is to
prevent any water which may be drawn back through the delivery
tube from entering the hot flask and probably breaking it. The
entrance and exit tubes of a safety bottle should not project much
below the lower surface of the cork.
EXPERIMENT 78. Acetylene by Action of Water
on Calcium Carbid. Place a few small lumps of cal-
cium carbid in a gas generator, and cover them with
strong alcohol. Slowly add water through the funnel
tube so as to cause a brisk evolution of the gas. Catch
a couple of receivers full and ascertain its physical
properties. With what kind of a flame does it burn ?
EXPERIMENT 79. Destructive Distillation. Fill a
test tube to a depth of about 3 cm - with excelsior or soft
coal, packing it in tight, and support the tube horizon-
tally between two rings of a retort stand (Fig. 34). Fit
in a cork and delivery tube, and heat the lower end of
the tube, gently at first, but finally as hot as possible
without melting the glass. Let the delivery tube dip
below the surface of the water in a pneumatic trough,
and from time to time catch a test tube full of the gas
given off, and test its inflammability. When no more
gas is evolved, remove the delivery tube from the
water. Test the liquid which has collected in the tube
near its mouth with blue litmus paper. What effect ?
What are the physical properties of the residue ?
EXPERIMENT 80. A Simple Gas Factory. Roll a
piece of paper (foolscap size) so as to form a cone with
one end about 0.5 cm - in diameter and the other 2 to 3 cm -
in diameter. Hold it vertically with the narrow end
up and set fire to the other end. Apply a flame to the
upper end a little above the paper. Does the escaping
gas catch fire ? When the paper has burned about a
third of its length, quench the flame by dipping it under
water. Unroll the paper and examine any deposit on
that part of it which formed the lining of the cone.
62
Elementary Chemistry
EXPERIMENT 81. A Candle as a Gas Factory.
Heat a small bit of a candle in an old test tube until
vapors are formed that, on escaping from the tube,
may be ignited. Blow out a candle flame and imme-
diately bring a burning match or
flame down towards the wick.
What evidence is there to show
that a gas is being given off ?
THE ATMOSPHERE
EXPERIMENT 2. (Quantitative^)
To Determine the Percentage
of Oxygen in the Air. Fill a
hydrometer jar nearly full of water
at the temperature of the room.
Pour a little water in a graduated
tube, place its open end in the
water in the hydrometer jar, and
let in air, if necessary, by raising it
up until it nearly fills the gradu-
ated portion. Lift the tube up
until the level of the water within
and without is the same and read
off the volume of the air. Note
the temperature of the water and
the reading of the barometer, and
reduce the volume read to stand-
ard conditions. Bend a copper wire
about twice as long as the graduated tube (Fig. 49) in a
V-shape, sharpen one end with a file, and stick on this
pointed end a piece of phosphorus which has just been
scraped clean under water. Immerse the phosphorus
on the end of the wire under the water in the jar, and
bring the tube down over it so that the phosphorus pro-
jects up into the air. What happens?
Fig. 49 DETERMINING THE
PERCENTAGE OF OXYGEN
IN THE AIR
Experiments 63
Let the apparatus stand for at least twenty-four
hours, then lift the tube up until the level of the water
inside and out is the same and the phosphorus is under
water, and read off the volume. Reduce this volume to
standard conditions after reading the temperature and
pressure. Remove the phosphorus and again scrape it
clean under water and replace it in the tube as before,
leaving it there until the next day. Again find the vol-
ume of the gas, reduce it to standard conditions, and see
if it is the same as before. Compute the percentage of
oxygen in the sample of air taken.
O 1 234567
Fig. 50 TEST TUBE AND SCALE FOR DETERMINING THE VOLUME OF OXYGEN
IN A GIVEN VOLUME OF AIR
EXPERIMENT 83. The Volume of Oxygen in Air.
Select a long, narrow test tube and cut a piece of paper
whose length has the same ratio to that of the test tube
as the scale has to the test tube in the figure (Fig. 50).
Bend the ends of the strip of paper together and crease
it in the middle, and do this a second and a third time.
Then straighten the paper out so as to form a scale of
eight equal divisions to serve as a measure of the vol-
ume of the test tube. Instead of the above, any rule
or scale may be used.
Fill the test tube about one-eighth full of dry pyro-
gallic acid, and, holding the test tube so that the thumb
may be three-eighths of the distance from the bottom,
pour in potassium hydroxid solution up to the level of
the thumb. Immediately close the tube with the
thumb and shake the air and solution well together for
64 Elementary Chemistry
several minutes. Open the test tube with the thumb
under water in a pneumatic trough (a beaker will do)
and let stand for a few minutes so that the air may
come to the temperature of the room. By means of
the scale measure the volume of the gas left in the
test tube, lifting it up so that the level of the water
inside and out may be the same. How many volumes
of air did you take ? How many volumes of gas have
you now? How many volumes of oxygen were ab-
sorbed ? What is the volumetric composition of air ?
EXPERIMENT 84. Action of Dust on the Precipita-
tion of Water Vapor. Fit a bottle (500 to 2,000 c - c -}
with a two-hole rubber stopper, through each of the
holes of which passes an L-tube which is connected
with a chlorid of calcium tube. To one of the calcium
chlorid tubes is attached a small bicycle pump or a
rubber bulb with a valve. Put enough water in the
bottle to fill it to a depth of about 2 cm -. Insert the stop-
pers tightly and, closing with the thumb one end of
the calcium chlorid tube not connected with the pump,
pump air in through the other. When the pressure has
become rather great, suddenly remove the thumb and
note what takes place in the bottle. Repeat several
times so as to make sure of the appearance of the phe-
nomenon. Fill the calcium chlorid tubes loosely with
cotton wool and pump in air as before. Do this a num-
ber of times so as to replace the air in the bottle with
air which has been freed from its dust particles by
filtration through cotton. Is there any change in the
phenomenon ? Let the bottle stand for several hours
and then pump filtered air into it. What happens ?
Let it stand for several hours longer and then do as
before. Now thrust a lighted match for an instant into
the neck of the bottle (after loosening the stopper) so
as to introduce some smoke, i. e., dust, into the bottle,
Experiments 65
and pump in filtered air. What happens ? What con-
clusion can be drawn as to the action of dust particles
in the formation of water drops from vapor ?
EXPERIMENT 85. (Quantitative^] To Find the
Weight of a Liter of Air. Melt off the top of one
tomato can and the bottom of another. Pierce a hole
about 3 mm - in diameter in the center of the bottom
melted off and solder over it a bicycle valve. 1
Solder this bottom on the can, the top of which was
removed. Connect with a bicycle pump, and pump in
air until the pump works very hard. Disconnect the
pump and weigh the can to centigrams.
Slip over the valve a piece of rubber tubing in which
has been placed a match with its head removed. Con-
nect the other end of the tubing with an aspirating
bottle, being sure to have the pressure in the bottle
equal to that of the atmosphere. Pinch the rubber
tubing around the match which should be resting in
the valve, and, pressing the match against the valve,
open it a little so as to let some of the air escape. Con-
tinue doing this until no more air escapes from the can.
As the air on expanding cools, wait a few minutes and
then open the valve again, having the vessel employed
to catch the water driven out of the aspirator at such a
height that the water levels are the same. Remove
the can and weigh it. The loss in weight represents
the weight of the volume of air which has escaped
from the can.
Measure the volume of this water expelled from the
aspirator either by weighing to decigrams or by means
of graduates. Reduce the volume to o and 760 mm -.
Calculate the weight of one liter of air.
J This valve must close perfectly air-tight even when the screw-
cap is not placed on it.
66 Elementary Chemistry
FIRE AND FLAME
EXPERIMENT 86. Kindling Temperature. I. Put
a few drops of carbon bisulfid into a beaker and cover
it with a card or glass slip. The vapor of the liquid
then mixes with the air in the beaker. Heat the end
of a glass rod to redness and thrust it into the beaker.
Be careful to have your face as far as possible from the
beaker. Repeat, using alcohol instead of carbon bisul-
fid. What are your conclusions in regard to the tem-
peratures at which different C9mbustibles take fire ?
II. Try to ignite illuminating gas with a spark (not
a flame) at the end of a match stick. Is the tempera-
ture of the spark high enough ? Press a piece of wire
gauze, held horizontally, down upon a Bunsen flame.
Give reasons for what you observe. Pinch the rubber
tubing together to extinguish the flame, and then, hold-
ing the gauze just above the orifice, light the gas above
the gauze. Raise the gauze up and note the behavior
of the flame. If the gauze were made of a material
which is a poor conductor of heat, how do you think it
would modify the phenomena observed ?
EXPERIMENT 87. Structure of Flame. I. A candle
flame. Examine a candle flame in a place free from
drafts, observing all its parts with their colors, and make
drawings of each part. Holding it before a blackboard
or other dark surface, note the outer portion. Also hold
it in direct sunlight and examine the shadow it casts on
white paper. Holding a piece of sized paper (asbestos
paper is better) horizontally with both hands, press it
down for a moment or so on the flame nearly to the wick,
and examine the charred or sooty portions of the paper.
II. A Bunsen flame. Repeat the above experiments
with a Bunsen flame instead of a candle flame. Hold a
match stick across the orifice of the burner and note how
Experiments 67
the wood is charred. Hold it just above the inner cone
and note what happens. Draw out one end of a piece of
glass tubing to a bore of a little less than a millimeter,
thrust the wider end into the inner cone and ignite the
gas escaping from the drawn-out end. Slowly raise the
tube until its wider end comes above the inner cone and
note what happens. Thrust a pin through a match near
its head and put the stick into a burner. Turn on the
gas and light it above the match. Hold a piece of new
asbestos paper or board vertically so as to divide the
flame in halves and note how it is charred.
EXPERIMENT 88. Luminosity of Flame. Sprinkle
a little charcoal dust into a non-luminous flame ; also
rub two pieces of charcoal together near the airholes
of a Bunsen burner so that the dust may be carried up
into the flame by the inflow of the air. What is the
effect upon the flame ? Stir up the dust in the vicinity
of a non-luminous flame. Close up the airholes of a
Bunsen burner, and essay an explanation for the lumi-
nosity of the flame thus produced. Examine a Wels-
bach burner and mantle. Wherein does the Welsbach
burner resemble the Bunsen burner ? What is the
function of the mantle?
EXPERIMENT 89. Speed of Propagation of Flame.
Slowly turn off the gas of a Bunsen flame so as to
diminish its speed of outflow very gradually. What
happens ? This is because the speed of flow of the gas
becomes less than that of the flame. Now turn the gas
full on. At what two orifices is the flame now burning ?
What was the cause of the slight explosion ?
EXPERIMENT 90. Oxidizing and Reducing Flames.
Cut out a little cavity in a piece of charcoal, pack it
nearly full of litharge (lead oxid), and direct the reduc-
ing flame of a blowpipe steadily upon it for some time.
Examine the lead obtained. Now place a bit of lead
6
68 Elementary Chemistry
in a cavity in a piece of charcoal and direct the oxidiz-
ing flame upon it. Note the fumes and the color of
the coating on the charcoal.
SALTS, ACIDS, AND BASES
EXPERIMENT 91. General Properties of Acids.
Fill a beaker with distilled water, and after rinsing off
a glass rod, dip it into the distilled water and place the
drop that adheres to it on the tongue, noting its taste.
Rinse the rod again it must be washed after each test
and by means of it place a drop of the distilled water
on a piece of blue and of pink litmus paper, being sure
that the paper is on a clean surface. What change of
color ?
Pour about io c - c - of the distilled water into a clean
test tube, add not more than three drops of strong sul-
furic acid, and stir well together. In the same manner
as before taste this acid solution and ascertain its action
on pink and on blue litmus paper.
Perform similar tests with very dilute solutions of
any other acids which are available, as nitric, acetic,
hydrochloric, tartaric.
Review Experiment 18 and state what is the general
action of dilute acids on metals. Test the action of acids
on any other indicators which may be available, such as
Congo red, phenolphthalein, methyl orange.
EXPERIMENT 92. General Properties of Bases.
Dissolve a piece (3 mm -) of sodium hydroxid in about
IQC.C. of water in a test tube. Pour a drop or so on
your finger and rub it with another finger. What is
the feel? Dilute a little of this solution with about
twenty times its volume of water, and, using a stirring
rod, cautiously taste a drop. If the taste is not decided
enough, add a little more of the sodium hydroxid solu-
tion. Find what effect the solution has on pink and on
Experiments 69
blue litmus paper as well as upon any other indicators
available. Repeat these tests with potassium hydroxid
instead of sodium hydrcxid ; also ammonium hydroxid
(review Experiment 54), and with lime water (calcium
hydroxid, Ca(OH) 2 , solution).
EXPERIMENT 93. Neutralization. Place about 5^-
of a very weak solution of sodium hydroxid in an evap-
orating dish, and add a little litmus solution or any
other indicator. Then with constant stirring add (a
drop or so at a time) dilute hydrochloric acid until the
blue color changes into a lavender. If too much acid is
added, the color will be pink. In that case add some
more sodium hydroxid solution, a drop at a time, so as
to get the color just blue, and then a very small drop
of the acid. When the intermediate color has been
obtained, evaporate to dryness. Examine the product
as to its physical properties and try its action on litmus
paper, as well as upon other indicators that you may hap-
pen to have at hand. What is the substance ? Repeat
these operations, using dilute nitric acid instead of
hydrochloric.
OXIDS OF NITROGEN; NITRIC ACID
EXPERIMENT 94. Preparation and Properties of
Nitrous Oxid. Put about 15^- (6 cm - circle) of ammo-
nium nitrate, NH 4 NO 3 , into a flask (or retort) provided
with a delivery tube and an interposed safety bottle 28
(Fig. 51). Heat the flask gently and collect a couple
of receivers full of the gas by water displacement.
Plunge a lighted splinter of wood into a receiver full
of the gas. Is the gas combustible or a supporter of
combustion ? Set a little red phosphorus or sulfur on
fire in a combustion spoon and introduce it into the gas.
What other gas behaves in a fashion similar to nitrous
oxid ? How would you distinguish the two gases ?
Elementary Chemistry
Fig. 51 APPARATUS FOR PREPARING NITROUS OXID
EXPERIMENT 95. Nitric Oxid ; Its Preparation
and Properties. Put about io& of copper 29 (in the
form of filings, turnings, bits of wire, or granulated) in
a gas generator; just cover it with water 30 and add
enough strong nitric acid to cause a brisk evolution of
the gas. Add water if the reaction becomes too tumul-
tuous. Collect by water displacement six receivers full
of the pure gas, saving two receivers full for Experi-
ment 98. Let a little of the gas escape from one of the
receivers. What causes it to turn brown as soon as it
comes in contact with the air ? Insert a lighted splin-
ter into one of the receivers. Is the gas combustible
or a supporter of combustion ? Introduce a combustion
spoon containing burning red phosphorus into a receiver
full. Compare the result with that obtained with
nitrous oxid.
NOTE 29. Ferrous Sulfate. Ferrous sulfate (also known as
green vitriol and copperas) may be advantageously substituted for
Experiments ji
the copper. It should be in the form of small lumps or crystals,
and strong nitric acid added. The reaction is more easily con-
trolled and a purer gas is obtained.
NOTE 30. Use Hot Water. As nitrous oxid is rather soluble
in cold water, it is advisable to have the pneumatic trough filled
with as hot water as convenient.
EXPERIMENT 96. Volumetric Composition of
Nitric Oxid. Obtain a glass tube about 20 cm - long
and of about i cm - bore, sealed at one end. Fit over the
open end a piece of tightly-fitting rubber tubing about
gem. long and have ready two Hofmann clamps (Fig.
52). Fill the glass and rubber tube with water and
then displace the water with pure nitric oxid, prepared
by the reduction of nitric acid by ferrous sulfate. Pinch
the tube tightly near the glass tube with one of the
clamps, A, and, removing the tube from the water, fill
the rubber tube nearly full with an intimate mixture of
equal bulks of powdered iron and sulfur. Then close
the tube near its end with the second clamp, B. Now
open the first clamp so that the mixture of iron and
sulfur may fall into the tube. Shake the tube at inter-
vals of fifteen to twenty minutes. Then turn the tube
upside down and shake as much as possible of the solid
Fig. 52 APPARATUS FOR DETERMINING THE VOLUMETRIC COMPOSITION
OF NITRIC OXID
mixture clown into the rubber tubing. Close the clamp
A, as before, open clamp />, and after shaking out the
solid mixture, fill the rubber tubing brimful of water,
close it with the thumb and place the tubing under
water. Now open clamp A What happens?
With a rubber band or piece of cotton cord mark the
volume of the gas remaining. What gas is it ? Ascer-
tain the volume of this and that of the nitric oxid taken
72 Elementary Chemistry
at first by running 1 in water from a burette or by weigh-
ing-. What conclusion do you draw as to the volume of
oxygen and nitrogen composing nitric oxid ?
* EXPERIMENT 97. Nitrogen Dioxid. Heat in a test
tube a few crystals of manganous nitrate, Mn(NO 3 ) 2 ,
or lead nitrate, Pb(NO 3 ) 2 . The main gaseous product
is nitrogen peroxid. Is it soluble in water ?
EXPERIMENT 98. Illustration of the Law of Vol-
umetric Proportions* Prepare two gasometric tubes
as follows : Obtain two test tubes about 2$ cm - long and
i cm - wide. Fill the small tube even full of water and
empty it into one of the large tubes, and mark the
position of the water level with a rubber band. Add a
second tube full and mark the position of the water
level, and continue in this way until the tube is full.
Proceed in like manner with the second large tube.
Introduce into one of the gasometric tubes two vol-
umes of nitric oxid (best prepared from nitric acid and
ferrous sulfate), and into the other, five volumes of air.
Pass the contents of one tube into the other. 31 What
is observed ? In two or three minutes read the volume
of the residual gas. What gas is formed when nitric
oxid comes in contact with oxygen ? Is it soluble in
water ? Explain the contraction.
Repeat this procedure at least twice, so as to be sure
of the results, each time transferring the residual gas
into a receiver so that it may be examined and tested as
follows : Measure out from the receiver three volumes
and add a measured volume of air. Is there any con-
traction ? If so, add some more air, and see if there is
any contraction. In the same fashion, add volumes of
nitric oxid to a measured volume of the residual gas
and continue the additions until there is no contraction.
Point out in detail how this experiment illustrates the
law in question.
Experiments
73
NOTE 31. Transferring Gases. To transfer gases from ne
vessel into another, the pneumatic trough must be deep enough
to allow of the complete submerging of the vessels. They are
then placed so that the gas from one may rise and displace the
water in the other.
EXPERIMENT 99. Preparation and Properties of
Nitric Acid. Put into a retort about 15 ff. (5 cm - circle)
of powdered soditim or potassium nitrate and add about
30 c.c. of strong sul-
furic acid. Arrange
the apparatus (Fig.
53) so that the retort's
neck passes nearly to
the bottom of a test
tube or flask set in a
dish filled with cold
water. Heat gently
with interposed wire
gauze, noting the be-
havior of the mixture
in the retort. When
the test tube is about a quarter full of the distillate
remove the flame ; be sure that the end of the retort's
neck is not dipping below the surface of the acid in the
test tube.
CAUTION. Be very careful not to spill nitric
acid on the hands; it produces very bad burns.
Note the color of the nitric acid thus prepared, and
compare it with that of a freshly-opened bottle of the
commercial "c. p." article. How do you account for
the difference ? Cautiously note its odor. Pour a few
drops on a glass plate or watch crystal and place beside
it a glass plate or watch crystal containing a little
strong ammonia water. How do you account for the
result ? Put a bit of litmus paper in a dish and add a
few drops of acid from the test tube ; repeat after
Fig. S3 PREPARING NITRIC ACID
74 Elementary Chemistry
diluting the acid with about four times its volume of
water. Take up a drop on a stirring" rod and touch it
to your finger-nail or a quill ; wash it off promptly and
put on a drop of ammonium hydroxid. Test its action
both when cold and when hot on a little of the follow-
ing metals placed in separate test tubes : iron, copper,
zinc, lead, and mercury. Pour a drop or so into a little
indigo solution. Put a drop on a piece of newspaper
and on a piece of the best linen writing paper. Is the
difference in the action sufficient to distinguish news-
paper (which is made from wood pulp) from writing
paper (which is made from Jinen rags)? What is the
paper of your notebook made of, wood pulp or linen?
EXPERIMENT 100. Decomposition of Nitric Acid
by Heat. Support a long-stemmed tobacco pipe on a
stand so that its mouthpiece just dips below the water
in a dish, Heat the stem red-hot with a Bunsen flame
and then pour a few drops of concentrated nitric acid
into the bowl so that it may flow down through the
heated portion. What makes the bubbles have a
reddish-brown color while the gas which collects in
the receiver is colorless ? Into what three substances
is the nitric acid decomposed ?
EXPERIMENT 101. Reduction of Nitric Acid to
Ammonia. Put a little granulated zinc into a test tube
and add about 5 c - c - of dilute sulfuric acid. After the
hydrogen is escaping freely, add a drop at a time (a
"medicine dropper" will be found convenient, or a little
pipette easily made by drawing out to a jet a piece of
glass tubing), very dilute nitric acid, noting carefully
what happens when each drop is added. Add only
about a dozen drops of the nitric acid. After a few
minutes pour part of the solution into another test
tube and add an excess of caustic soda solution. Warm
a little and cautiously smell of the contents of the tube.
Experimcn ts 75
What evidence is there that ammonia is being given
off ? Verify your conclusion by the use of litmus paper
and by Nessler's solution. How do you explain the
formation of the ammonia ?
EXPERIMENT 102. Reduction of a Nitrate to a
Nitrite. Heat 15^- of sodium or potassium nitrate with
30^- of lead in an iron dish (sand bath pan), stirring the
melted mixture with a stiff iron wire or long nail until
most of the lead has disappeared. Transfer the cooled
mass to a mortar, grind it to a powder, add hot water,
stir well and filter. To a portion of the filtrate add a
few drops of concentrated sulf uric acid, or potassium or
barium nitrate. The yellowish-brown powder formed
during the heating is lead oxid. What is the source of
the oxygen combining with the lead ? How must the
nitrate have been changed ?
PREPARATION AND PROPERTIES OF ACIDS,
BASES, AND SALTS
EXPERIMENT 103. Preparation of a Salt (Mercury
lodid) by Direct Union of the Elements. Weigh on
a watch glass 2.5^- of mercury 32 , and then also on a
watch glass ^.2^- of iodin 33 . Place the mercury in a
clean mortar and just cover it with alcohol 34 . Add
about a quarter of the iodin and rub it gently into the
mercury until the iodin as such seems to have dis-
appeared. Then mix in a second quarter-portion and
continue until all the iodin is added and the mixture is
dry and of a bright red color. Transfer the product to
a test tube and add about 5 c - c - of alcohol. Heat the
alcohol to boiling for a minute or so by immersing the
end of the tube in boiling water contained in a beaker.
Pour the solution into an evaporating dish and set
aside to cool. Examine carefully the crystals of mer-
cury iodid which separate out. Place a few of them
76 Elementary Chemistry
in a dry test tube and cause them to sublime by heat-
ing the rounded end of the tube. How do you account
for the different colors of the sublimate ? Rub it with
a glass rod and note any change of color 35 .
NOTE 32. Pipette for Handling Mercury. A convenient way
to handle small quantities of mercury is by means of a little pipette
made by drawing out a piece of narrow glass tubing to a long,
tapering point. Mercury is drawn up into the pipette by suction.
If the tube then be held in an almost horizontal position, the
mercury will not run out, and may be nicely discharged where
wan ted" by inclining the pipette a little.
NOTE 33. Danger of Corrosion. As both mercury and iodin
corrode brass, great care must be exercised not to let them or their
fumes come in contact with the brass parts of a balance. Be sure
to collect any of either element whteh may become scattered about
the balance through careless handling.
NOTE 34. Addition of Alcohol. The reason for adding alcohol
is to keep down the temperature (the heat of the reaction will be
expended largely in evaporating the alcohol) and to bring the
iodin and mercury in more intimate contact. The alcohol does
not participate in the reaction at all.
NOTE 35. Iodin Stains. Iodin stains may be removed by
means of sodium sulfite or ammonium sulfid solution.
EXPERIMENT 104. Preparation of a Salt (Zinc Sul-
fate) by the Solution of a Metal (Zinc) in an Acid
(Sulfuric). Place about 5^- of zinc in a beaker or flask
and add about 40 c - c - of dilute sulfuric acid. When the
evolution of hydrogen has nearly ceased, filter the solu-
tion into an evaporating dish and gently heat 3 6 over a
wire gauze nearly to boiling, until a thin film appears
on the surface of the solution. Then set it aside so
that it may cool slowly. At frequent intervals for
several days examine the crystals which separate out
and carefully note their form. Remove them from the
solution and dry them by pressing between folds of
filter paper. Do the crystals contain water of crystal-
lization ?
NOTE 36. Slow Evaporation. Instead of evaporating off the
water rapidly by heating, the dish may be set aside so that the
water may slowly evaporate during several days. If this be
done, better and larger crystals will be obtained.
Experiments
77
EXPERIMENT 105. Preparation of a Salt (Ammo-
nium C/tlorid) by the Neutralization of Ammonium
Hydroxid by Hydrochloric Acid. Dilute 25 c-c. of con-
centrated hydrochloric
acid with an equal vol-
ume of water, mix well,
and fill a burette with the
mixture 3 7 . Fill a second
burette with concentrated
ammonium hydroxid
(Fig. 54). Run 5.0^- of
the acid into an evaporat-
ing dish which has pre-
viously been weighed to
centigrams, and add just
enough litmus solution to
impart a distinctly pink
color. Note the reading
on the burette containing
the ammonium hydroxid,
and run the solution, a
few drops at a time, into
the acid, with constant
stirring, until the red
color turns to blue. Then
run in the acid, drop by
drop, stirring after each
addition, until the color is
half-way between blue and
red. Evaporate the solu-
tion to dryness on a water
bath 2 2 (the ammonium chlorid volatilizes at a higher tem-
perature), let cool and weigh. Again heat for a quarter of
an hour and weigh, continuing in this way until the salt
is perfectly dry, as shown by no further loss in weight.
Fig. 54 BURETTES ARRANGED FOR NEU-
TRALIZING A BASE BY AN ACID TO PRO-
DUCE A SALT
78 Elementary Chemistry
The equation for this neutralization reaction may be
written thus :
NH 4 OH + HC1 -> NH 4 C1 + H 2 O
How many grams of NH 4 C1 have you prepared ? Calcu-
late how much NH 4 OH and HC1 were needed. How
much NH 4 OH and HC1 were contained in the volume
of the solutions used? Calculate how many grams of
NH 4 OH and of HC1 there would be in a liter of a solu-
tion of the same concentration.
NOTE 37. Drying the Burette. If the burette is not perfectly
dry, it should be rinsed out, delivery tube and all, with a few
cubic centimeters of the acid before filling. The ammonium
hydroxid burette should also be rinsed out with that liquid.
EXPERIMENT 106. The Solubility Product. Pre-
pare a saturated solution of sodium chloric!, NaCl, by
shaking the solid in a test tube with water until no
more is dissolved. The solution will not be accelerated
by heating, as sodium chlorid is nearly as soluble in
cold water as in hot. Fill a test tube a quarter full
with this saturated solution. Put a few cubic centi-
meters of concentrated hydrochloric acid in a test tube
provided with a cork and delivery tube, heat gently,
and pass the hydrogen chlorid expelled from solution
into the solution of salt. Prove experimentally that
the white substance precipitated is sodium chlorid, and
explain its formation.
THE HALOGENS AND THEIR HYDROGEN
COMPOUNDS
EXPERIMENT 107. Chlorin by Oxidization of Hy-
drochloric Acid. Into separate test tubes put a pinch
of potassium chlorate, of red lead, and of potassium
dichromate, and add a little strong hydrochloric acid to
each. If a reaction does not take place promptly, warm
a little. Note the physical properties of the gaseous
Experiments
79
product, and then stop the action by filling the tube up
with water. What are the color and other properties
of this solution ?
EXPERIMENT 108. Preparation of Chlorin. I.
(Hood.) Into a flask (200 to 300 c - c -} fitted with a delivery
tube and an interposed safety bottle (Fig. 55), put about
20 ff- (5^- circle) of
manganese dioxid
and add to it 50^-
strong hydro-
chloric acid. The
delivery tube
should reach to
the bottom of the
receiver, which
should be snugly
covered with a
piece of cardboard
pierced with a
hole for the pas-
sage of the delivery tube. Heat the flask gently and
collect by downward displacement four receivers full
of the gas. You can tell by the greenish color when
the receivers are full, and the full receivers should be
covered with glass slips smeared with a little vaseline
so as to make gas-tight joints. Pass to Experiment no.
EXPERIMENT 109. Preparation of Chlorin. II.
(Hood.) Into a gas generator fitted with a stopcock
funnel (Fig. 18) put about enough of bleaching powder
to cover the bottom of the generator to a depth of a
centimeter. The delivery tube should reach to the bot-
tom of the receiver, which should be covered with a
piece of cardboard with a hole through it for the passage
of the delivery tube. Let strong hydrochloric acid drop
from the funnel upon the bleaching powder just fast
Fig. 55 PREPARING CHLORIN
8o Elementary Chemistry
enough to keep up a brisk evolution of the gas, and col-
lect four receivers full by downward displacement, cov-
ering a receiver when full (as shown by the green color)
with a glass slip smeared with vaseline. Pass to Ex-
periment no.
EXPERIMENT no. Properties of Chlorin. (Hood.)
Thrust a piece of flaming paper into a receiver filled
with chlorin, moving the glass slip only a little aside
and at once covering the receiver again so as to prevent
the fumes from escaping. Is the gas combustible?
Does it support combustion ? Moving the glass slip
aside again, sprinkle a pinch of powdered antimony
into the gas. Also introduce a loose bundle of very
fine brass or copper wires which have been heated to
redness. Is the gas a supporter of combustion ? Com-
pare it in this respect with oxygen.
Into a second receiver put some paper with writing
(both by ink and by pencil) on it and some pieces of
dry calico, and into a third some paper with writing on
it and some pieces of moistened calico. What differ-
ences are to be observed in the bleaching action in the
two receivers ? Repeat with the fourth receiver any of
the above experiments, the results of which you are in
doubt about and wish to verify.
EXPERIMENT m. Chlorin Water. Drop into a
test tube a few small crystals of potassium chlorate,
cover them with concentrated hydrochloric acid diluted
with an equal volume of water, warm a little, and as
soon as the chlorin begins to escape from the tube, fill
it nearly full of water. Pour a little indigo solution
into a test tube and add an equal volume of the chlorin
water. Is the color discharged ? Try the action of the
chiorin water on solutions of litmus, of cochineal, and
of copper sulfate. Explain any differences in the
bleaching action.
Experiments
81
EXPERIMENT 112. Preparation and Properties of
Bromin. Put about 10^- (^ cm - circle) of potassium
bromid in a mortar and add an equal bulk of man-
ganese dioxid. Mix them well together and introduce
the mixture into a dry retort, and then add about io c - c -
of concentrated
sulfur ic acid.
Support the re-
tort on the stand
so that its neck
may enter a test
tube or flask set
in a dish filled
with cold water
(Fig. 56). Put a
little water in the
test tube and ad-
just so that the
neck of the retort just dips into the water. Heat the
retort very gently and collect the bromin given off until
no more red vapor is seen in the retort. Note the phys-
ical properties of the bromin.
Pour a drop or so of bromin into a dry receiver,
cover with a piece of paper or a glass slip, and shake
and invert the receiver so that the bromin may rapidly
vaporize and its vapors fill the vessel. Try its bleach-
ing action as was done with chlorin and compare
results. Pour what bromin is left into the bottle
labeled "Bromin" which is standing on the side table.
EXPERIMENT 113. Preparation and Properties of
lodin. Grind well together in a mortar a half dozen
crystals of potassium iodid with an equal bulk of man-
ganese dioxid, put the mixture in an Erlenmeyer flask,
and add about 15^- of a mixture of equal volumes of
concentrated sulfuric acid and water. (Pour the acid
82
Elementary Chemistry
into the water, not the water into the acid.) Set the
flask on a wire gauze on a ring stand, and insert in
its neck loosely a perforated cork holding a small test
tube filled with cold water (Fig. 57). Another appara-
tus is a tall, slender beaker with a watch glass cover-
ing it and filled with cold
water (Fig. 58). Heat the
flask with a very small
flame, just enough to
cause the iodin liberated
from the potassium iodid
to vaporize and collect on
the sides of the test tube
kept at a low temperature
by the cold water. When
the test tube is covered
with crystals of iodin, dis-
continue the heating, re-
move the test tube, and
scrape the iodin into an
evaporating dish. Note
its physical properties.
Fig. 57 PREPARING IODIN ' ln J 1 .
Heat a small crystal in
a dry test tube and when the tube is filled with the
vapor, invert it and draw conclusions as to the relative
weights of air and iodin vapor. Touch your finger to
a crystal. What is the color of the stain ? Will water
remove it ? Will alcohol ? Will a solution of potassium
iodid? In which of these three liquids is iodin readily
soluble? Place the rest of the iodin in the bottle
labeled " Iodin " which is standing on the side table.
EXPERIMENT 114. Tests for Free Bromin and
Iodin. Prepare a test tube full of chlorin water (Ex-
periment in). Dissolve a bit of potassium iodid and of
potassium bromid not larger than a pinhead in a small
Experiments
test tube a quarter full of water, a different test tube
for each substance. Make some thin starch paste by
rubbing up a small lump (5 mm -) of starch with a little
water in a mortar to the consistence of cream, and then
boiling it in an evaporating dish with about 50^- of
water until it is clear.
Pour three or four
drops of this starch
paste into 10^- of
water in a test tube
and shake it up well ;
then add a drop of an
aqueous solution of
iodin. What is the
change in color?
Heat the solution
gently until the color
disappears, and then
cool it by immersing
in cold water. This
is a very delicate test
for iodin when not in
Combination. Repeat Fig. 58 ANOTHER APPARATUS FOR PREPAR-
this test, using bro-
min water instead of an iodin solution. Is the test as
decisive as for iodin ?
Pour three or four drops of starch paste into 10^-
of water in a test tube, shake it up well, and add a drop
or so of the solution of potassium iodid you have pre-
pared. Is there any change of color ? Now add a dozen
or so drops of the chlorin water. Explain what occurs.
Repeat with the solution of potassium bromid instead
of the iodid. Compare the results.
Put a couple of drops of an aqueous solution of
iodin in about io c - c - of water in a test tube, add about
84 Elementary Chemistry
2 c-c. of carbon bisulfid, and shake the two liquids well
together. Does the color of the carbon bisulfid change ?
Repeat, using a solution of bromin instead of iodin.
Compare the two results. Repeat, using a solution of
chlorin water. Does this give a decisive test ?
Add about 2 c - c - of carbon bisulfid to the solution of
potassium iodid prepared and shake them well together.
Does the color change? Add a few drops of chlorin
water and shake. What result? Repeat, using the
solution of potassium bromid. Compare results. Could
you prove by these tests that bromin was present in a
solution of unknown composition if iodin was also pres-
ent? Try it on a mixture of potassium bromid and
potassium iodid solutions.
EXPERIMENT 115. Action of Concentrated Sulfuric
Acid on Halid Salts. Place in separate test tubes a
couple of small crystals of sodium chlorid, of potassium
bromid, and of potassium iodid, and add to each about
2 c - c - of concentrated sulfuric acid. Cautiously compare
the smells of the gases evolved. Heat gently and note
the appearance of any colored gases, if they have not
been noticeable without heating. What elements are
set free ?
Put a pinch of calcium fluorid (fluorspar) in a small
test tube and add about 2 c - c - of concentrated sulfuric
acid. Heat until a gas is given off vigorously. Note
the physical properties of this gas and after five min-
utes or so pour out the reacting mixture into a plentiful
supply of water. Wash out the test tube and see if the
glass has lost its transparency in spots, and if so, account
for it.
To clean the test tubes pour their contents out into
a large amount of water. Do not run water into tJie
tubes upon the hot sulfuric acid, as there is danger of an
explosion.
Experiments
EXPERIMENT 116. Preparation and Properties of
Hydrochloric Acid. Put io c - c - of cold water in a
beaker and add to it slowly and with constant stirring,
SQC.C. of concentrated sulfuric acid. Set the mixture
aside to cool. Put about 30^- (6 cm - circle) of common
salt in a flask provided with a safety bottle and delivery
tube, to the end
of which may be
attached a small
funnel (Fig. 59)
or a straight piece
of large glass tub-
ing. Add the cold
acid and heat
gently with the
funnel attached
to the end of the
delivery tube, un-
til the gas given
off is nearly all
absorbed by the
water in which
the rim of the funnel just dips. Then collect by down-
ward displacement four dry receivers of the gas, cov-
ering them with glass plates when full. Let the gas
pass into some distilled water contained in a dish, using
the funnel attachment, and save the solution for Expe-
riment 1 1 8.
Invert a receiver full of the gas and, holding its
mouth under water in a pneumatic trough, open it.
How do you account for what happens ? What other
gas studied has exhibited a similar property ? Thrust
a blazing splinter of wood into a second receiver. Does
the gas burn or support combustion ? Hold a piece of
wet filter paper over the mouth of another receiver.
Fig. 59 PREPARING HYDROCHLORIC ACID
86 Elementary Chemistry
What is the cause of the phenomenon? Drop in the
last receiver a piece of filter paper moistened with
strong" ammonia water. What happens ? What is the
substance formed ?
EXPERIMENT 117. Analysis of Hydrogen Chlorid.
(a) Place a bit (3 ) of sodium in a bulb tube (Fig. 60),
support it horizontally, and connect it on one side with a
generator from which a brisk
current of hydrogen chlorid
(generated by dropping con-
Fig. 60 sutB TUBE centrated sulfuric acid into
concentrated hydrochloric acid contained in a stopcock
generator) is issuing, and on 'the other with a delivery
tube. As soon as all the air has been swept from the
tube (How can that be told?), heat the sodium cau-
tiously until it takes fire. Now collect in a test tube a
sample of the gas given off and discharge it into a flame.
What is the gas ?
When the sodium no longer burns, disconnect the
generator (letting the gas pass into water by means of
a funnel, as described in Experiment 116), and, after
the bulb tube has cooled, break it open and prove by
appropriate tests that common salt, NaCl, has been
formed. In the burning of the sodium, what substances
were the combustible and the supporter of combustion,
respectively ?
(b) Put some manganese dioxid into an evaporating
dish and heat as hot as possible for about ten minutes
so as to remove all moisture from the dioxid. Arrange
an apparatus . as shown in Fig. 31. Place in the tube
some of the manganese dioxid and connect with the gas
generator. As the hydrogen chlorid passes through
the tube, heat the manganese dioxid gently by just
brushing a flame along the tube. Collect the gas given
off over water and establish its identity by suitable tests.
Experiments 87
How do you account for the moisture that collects just
beyond the dioxid ?
EXPERIMENT 118. Tests for Chlorids, Bromids,
and lodids. Prepare dilute solutions (about 3 per cent)
of sodium chlorid, of potassium bromid, and of potas-
sium iodid. To a few drops each of these solutions add
an equal volume of silver nitrate solution. Compare
the colors and properties of the precipitates. Boil the
solutions and note the behavior of the precipitates. Add
ammonium hydroxid until pieces of litmus paper placed
in the tubes are blue, shake well, and note which pre-
cipitates dissolve. What is the effect of adding enough
nitric acid to make the litmus red ?
Add silver nitrate solution to a little of the solution
of hydrogen chlorid prepared in Experiment 116, and
to as many chlorids, bromids, and iodids as are available.
How do all the results compare ? How can a test for a
fluorid be devised from Experiment 115 ?
EXPERIMENT 119. {Quantitative.} To Find the
Atomic Weight of Chlorin. Clean, dry, and weigh
to centigrams an evaporating dish. Fill it about one-
fourth full of finely powdered sodium chlorid and heat
until decrepitation ceases. Let cool and weigh. Cover
the salt with strong nitric acid, evaporate to dryness on
a water bath, and heat with free flame until the sodium
nitrate which has been formed just begins to melt. Let
cool and weigh. To make sure that all the chlorin has
been expelled, moisten the salt with concentrated nitric
acid, heat and weigh again, repeating until a constant
weight is obtained.
The reaction is :
NaCl + HN0 3 > NaNO 3 + HC1
A known weight (a) of sodium chlorid is converted into a
known weight (6) of sodium nitrate. If the atomic weight of
chlorin be denoted by .r, and those of sodium, nitrogen, and
88 Elementary Chemistry
oxygen arc 23, 14, and 16, respectively, then the molecular weight
of NaCl is: + ^
and that of NaNO 3 is :
23 + 14 + (3 X 16)1=85
a 23 + x
Then -=
b 8
85 a 23 b
and x =
b
EXPERIMENT 120. (Quantitative^ To Ascertain
the Strength of a Given Sample of Hydrochloric
Acid. Fill a burette with the acid to be tested. Put
about IQC-C- of a 5 per cent solution of sodium hydroxid
in an evaporating dish, and add a few drops of some
indicator. Run the acid into the alkali with constant
stirring until neutralization is obtained. Evaporate to
dryness without spattering. Heat the dish to constant
weight. Calculate the weight of hydrogen chlorid in
one liter of the solution.
The equation for the neutralization of sodium hydroxid by
hydrochloric acid is :
NaOH + HC1 > NaCl + H 2 O
40 + 36.5 58-5 + 18
from which it is seen that 58. $& of NaCl are formed when 36. 5
of HC1 are used. The weight of the HC1 in the volume of the
solution taken stands then in the same ratio to the weight of the
NaCl found as does 36.5 to 58.5. The weight of HC1 contained
in a liter of the acid solution is calculated by means of the pro-
portion :
Volume of acid taken inc-c. Weight of acid found
1,000 c - c - x
EXPERIMENT 121. (Quantitative^] To Find the
Strength of a Given Sample of Nitric Acid. The
directions of Experiment 1 20 apply to rinding the
strength of a given sample of nitric acid ; sodium
nitrate is formed.
Experiments 89
THE ALKALI METALS
EXPERIMENT 122. Properties of Sodium and
Potassium, (a) Examine a small piece of sodium ;
note its most obvious properties, such as color, luster,
and hardness. Cut a slice off it and immediately note
the metallic luster. Review Experiment 23 (action of
sodium on water). Cautiously dissolve a small piece
in a little water in an evaporating dish. What is the
action of the solution on litmus ? Evaporate to dryness
and examine residue carefully. What is it ?
(b) Repeat (), using" potassium.
EXPERIMENT 123. Preparation and Properties of
Potassium Carbonate, (a] Fill a test tube half full of
hardwood ashes, cover with water, shake well together,
warm gently and filter. Test the filtrate (i) with both
blue and pink litmus paper, (2) for potassium (Experi-
ment 127), and (3) for a carbonate (add HC1 ; a result-
ing effervescence indicates CO 2 ).
(b} Put about 5^- (4^- circle) of cream of tartar
(acid potassium tartrate) in an iron dish and heat
strongly in the hood until the residue is white. Grind
the residue in a mortar with water, filter, and apply the
same tests as in (a).
(c) Mix thoroughly about 5^- (^ cm. circle) of pow-
dered potassium nitrate with an equal bulk of powdered
charcoal, and place the mixture in an evaporating dish.
Heat an iron dish or plate red-hot and, standing at
arm's length and grasping the evaporating dish with
tongs, pour the mixture upon the iron. If it does not
deflagrate at once, heat still hotter, being careful not
to have your face or hands above the mixture. When
deflagration has occurred and the product is cool, grind
it in a mortar with a little water, filter, and test the ni-
trate as in (a}.
90 Elementary Chemistry
EXPERIMENT 124. Preparation and Properties of
Sodium and Potassium Hydroxids. Make a solution
of about 50 & (10 cm - circle) of sodium carbonate in about
300 c-c. of water and place it in an iron dish. To about
20 ff- of lime add enough water to slake it and make a
milky mixture, "milk of lime." Heat the sodium car-
bonate solution to gentle boiling, add the milk of lime
and boil for five minutes, stirring constantly with a large
nail or a file. Let the precipitate settle, draw off a
little of the clear liquid with a tube drawn out so as to
form a small pipette, 3 2 transfer it to a test tube and add
an equal volume of dilute hydrochloric acid. If there
is effervescence, all of the 'sodium carbonate has not
been changed into the hydroxid ; so add a little more
milk of lime and boil. If there is no effervescence,
decant the clear liquid into a beaker. As sodium
hydroxid attacks glass and porcelain, it is not advisable
to evaporate the solution to dryness. The solution may
be preserved in a rubber-stoppered bottle, labeled
"Sodium Hydroxid," for use in subsequent work.
Examine a piece of commercial sodium hydroxid
and note its most prominent physical properties.
Potassium hydroxid is to be prepared according to
the same directions as given for sodium hydroxid, using
potassium carbonate instead of sodium carbonate.
EXPERIMENT 125. Preparation and Properties of
Ammonium Amalgam. Put about 2 c - c - of mercury
into a dry test tube, add a small piece (2 "**) of sodium,
cork the test tube very loosely, and heat gently. As
soon as a flash of light has indicated that the sodium
has formed an amalgam with the mercury, introduce
another piece of sodium, heat, if necessary, as before,
and continue in this way until the amalgam has become
solid. (An evaporating dish may be used instead of
the test tube.)
Experiments 91
Put about io c - c - of a strong solution of ammonium
chlorid in an evaporating dish, and introduce into it
about a quarter of the sodium amalgam. (The test
tube will probably have to be broken to get the amal-
gam out.) How does the amalgam change ? Take up
some of the substance in the fingers and describe its
"feel." What class of substances give this " feel " ?
Put the rest of the sodium amalgam into a test tube,
fill nearly full with strong ammonium chlorid solution,
and when the ammonium amalgam begins to run out of
the tube, fill it completely full with water, close with
the thumb and invert over water. Try to keep as much
of the ammonium amalgam as possible under the mouth
of the test tube so that the gas which forms may be
collected therein. When the test tube is full, test the
gas. What is it?
EXPERIMENT 126. Solvay Process of Sodium Car-
bonate Manufacture. Prepare saturated solutions
(about 100 <:) of ammonium carbonate and of sodium
chlorid by shaking the finely powdered salts for some
time with water. Decant the saturated solutions and
pass washed carbon dioxid into the ammonium car-
bonate until no more is absorbed. Now mix the two
solutions, stir well, and run in carbon dioxid. If a pre-
cipitate does not appear in a few minutes, shake well
for some time, and run in carbon dioxid again. When
a considerable amount of the precipitate has formed,
prove it to contain carbon dioxid and sodium by appro-
priate tests.
EXPERIMENT 127. Flame Tests. Wash apiece of
platinum wire as clean as possible and then hold it ir>
a Bunsen flame until the latter is no longer tinged by
vt. Dip its end in some sodium compound and bring
into the flame ; note the color. Clean the wire again,
dip into some potassium compound, and hold in the
92 Elementary Chemistry
flame. Unless the potassium compound is entirely free
from an admixture of sodium compounds, its character-
istic color will be masked by that of sodium. When the
flame is observed through cobalt blue glass, however,
as the sodium flame color is absorbed, that of potassium
alone is seen.
If a lithium salt is available, familiarize yourself
with its flame test also.
EXPERIMENT 128. Preparation and Properties of
the Nitrates of the Alkali Metals, (a) Put a little
sodium hydroxid (or carbonate) into a dish, add a little
water, and with constant stirring dilute nitric acid
until a slightly acid reaction, (litmus paper) is obtained.
Set the dish aside and examine it from day to day.
(b) Go through similar operations with potassium
hydroxid or carbonate instead of sodium.
(c) When crystals have formed from both solutions,
remove several specimens of each and compare their
shape carefully. Write a careful description of each.
Do you now see any reason for calling sodium nitrate
cubical niter, as is sometimes done ?
(d) Heat a few crystals of potassium nitrate in a
test tube until they melt and effervesce. Now drop
into the tube a piece (2 ) of charcoal. Describe what
happens. Repeat with sulfur instead of charcoal.
EXPERIMENT 129. Test for a Nitrate. Fill a small
test tube about a fifth full of clear crystals of ferrous
sulfate (green vitriol), and then about half full of water.
Shake until a clear solution results. To this add a
crystal of potassium nitrate about the size of a pin-
head.
Fill another test tube about a sixth full of concen-
trated sulfuric acid and, holding both test tubes as
nearly horizontal as possible, run the solution upon the
sulfuric acid so that the two liquids mix as little as
Experiments 93
possible. The brown ring shown where the solution
floats upon the acid indicates the presence of a nitrate.
Make a fresh solution of ferrous sulfate, and repeat
the test without adding 1 potassium nitrate. Does the
brown ring appear?
EQUIVALENT WEIGHTS
EXPERIMENT 130. (Quantitative^) Equivalent of
Sodium. Weigh out to centigrams a piece of clean
lead foil about 10 cm - square. Cut off a piece of sodium
(about 4 mm - long and 2 mm - cross section), scrape off
the coating of oxid and, after wiping it dry on filter
paper, roll it into a cylindrical form. The weight of
this cylinder should be about 0.9^-. Carefully roll the
sodium up in the foil, leaving one end open, but pinch-
ing the other end tightly together. By this arrange-
ment the exposed surface of the sodium alone can be
acted upon by water, and the evolution of hydrogen is
quite steady. Weigh to centigrams the sodium and foil.
The weight of the sodium is found by subtracting the
weight of the foil from that of the foil and sodium.
Fill a 500 c - c - graduated cylinder with water, close it
with a piece of paper, and invert it in a pneumatic
trough containing only a shallow depth of water. Drop
the sodium wrapped in the foil in the water and at once
place over it the inverted cylinder to catch all of the
escaping hydrogen. When no more gas is given off,
bring the water inside and outside the cylinder to the
same level by raising the cylinder or by pouring water
into the trough, and read off the volume. Also read
the barometer and the thermometer. Reduce the vol-
ume to standard conditions, correcting for aqueous ten-
sion, and multiply the reduced volume by 0.09 (the
weight of a liter of hydrogen) to find the weight of
hydrogen evolved. The quotient obtained by dividing
94 Elementary Chemistry
the weight of the sodium by that of the hydrogen is the
equivalent of sodium.
EXPB:RIMENT 131. (Quantitative^) Equivalent of
Zinc. I. Weigh out to centigrams about 5 & of zinc
(chemically pure, if possible), and put it into a gas gen-
erator provided with a stopcock funnel. Connect the
generator with an aspirating bottle (Fig. 24) of at least
2 l - capacity. Cover the zinc with a little \vater and
close the stopcock. The delivery tube is placed in a
vessel of water with the levels of the liquid in the ves-
sel and in the aspirator the same when the delivery
tube is open. Close the delivery tube and place it in a
tared bottle or beaker holding at least 2 / -.
Measure out with a pipette or a graduate 50^- of
strong hydrochloric acid, put a portion of it in the stop-
cock funnel, open the cock cautiously and let the acid
run into the generator; be very careful to prevent any
air being drawn into the generator. Add the acid from
time to time so as to keep up a rapid evolution of the gas.
When no more hydrogen is given off, add all of the
acid, if it has not already all been added, arrange the
aspirating and receiving bottle so that their water
levels are the same and, opening the stopcock, let the
acid drain into the generator. Let the apparatus stand
for several minutes to come to the temperature of the
room, and then close the delivery tube and lift it out of
the receiving vessel. Weigh or measure the volume of
the water expelled from the aspirator by the hydrogen,
read the barometer and thermometer, and reduce the
volume to standard conditions, allowing for aqueous
tension. Multiply this reduced volume by 0.09 (the
weight of a liter of hydrogen) to get the weight of the
hydrogen evolved. Divide the weight of the zinc by
the weight of the hydrogen ; the quotient is the equiv-
alent of zinc desired.
Experiments 95
EXPERIMENT 132. (Quantitative^ Equivalent of
Magnesium. The apparatus and operations are like
those in Experiment 131 : about 2?- of the metal should
be taken.
EXPERIMENT 133. (Quantitative.} Equivalent of
Zinc. II. (Hood.) Clean, dry, and weigh to centi-
grams an evaporating dish, together with a funnel,
which, when inverted, fits securely into the dish. Put
3 to 4-?- of zinc (preferably chemically pure, although
ordinary or mossy zinc will do) in the dish, replace the
funnel and weigh to centigrams. Support the dish on
a ring of a stand, and pour in beside the funnel a little
strong nitric acid so that it can flow under the funnel
and attack the zinc. As soon as the action subsides a
little, add more acid, and continue in this way until all
the acid is dissolved. Now evaporate to dryness, using
a large flame. When the contents of the dish appear
dry, gradually increase the heat, finally heating as hot
as possible for at least five minutes. Let the dish cool
and weigh it. Again heat to redness for several min-
utes and weigh, continuing in this way until the dish
and contents do not lose more than 3 c s- on heating.
The substance remaining is zinc oxid ; the zinc
nitrate at first formed is decomposed by the heating.
How many grams of zinc oxid have you obtained?
How much oxygen has combined with the zinc taken ?
What is the ratio of the weights of the zinc and oxy-
gen ? Taking the equivalent of oxygen as 8, what is
the equivalent of zinc as deduced from this experi-
ment?
EXPERIMENT 134. (Quantitative^ To Determine
the Vapor Density of Alcohol by Dumas' Method.
Fit a clean, dry flask (100 to 250 c - c -) with a one-hole
rubber stopper through which is thrust a bit of glass
tubing with its upper end drawn out to a diameter of
Elementary Chemistry
about a millimeter (Fig. 61), and after rubbing the
stopper with a little vaseline so as to make it fit
gas-tight, weigh the apparatus to centigrams (or better,
milligrams). Take
the temperature and
pressure of the air.
Put about 20 c - c - of
alcohol into the flask
and immerse it up to
its neck in boiling
water contained in a
beaker or can, hold-
ing it submerged by
means of a clamp.
Take the temperature
of the boiling water.
When the alcohol has
almost all boiled
away bring a Bunsen
flame to the tip of the
glass tube, and as
soon as the alcohol
flame goes out (an in-
dication that the flask
contains only alcohol
vapor) seal off.
Weigh the flask
again with the same
degree of accuracy as
before. Hold the neck of the flask under water and
with tongs or pinchers break off the tip of the sealed
tube. The flask should promptly fill almost completely
with water; if it does not, the experiment must be
repeated. Weigh the flask thus filled with water, to
decigrams only, on a platform balance. The difference
Fig. 6l DETERMINING THE VAPOR DENSITY
OF ALCOHOL
A short piece of rubber tubing, closed by a pinch-
cock, is substituted for the glass tip
Experiments 97
between the weights of the flask filled with water and
with air gives the weight of the water, which, as one
cubic centimeter of water weighs one gram, also gives
the volume of the air and of the alcohol vapor.
The calculation of the results are given on page 215
of the text.
SULFUR AND ITS COMPOUNDS
EXPERIMENT 135. Properties of Sulfur, (a) Re-
view the observations you made on sulfur in Experi-
ments i and 2.
(b) Fill a test tube nearly half full of sulfur and,
grasping it with a holder, heat it carefully. What is the
color of the sulfur just after it melts ? Pour a drop or
so into cold water and compare the product with the
original sulfur taken. Heat the tube so as to raise the
temperature of the melted sulfur gradually, and from
time to time tilt the tube. What changes occur in its
color and viscosity ? Do you find that at a certain tem-
perature the sulfur becomes so viscid that you can invert
the tube without the sulfur running out ?
Heat to boiling. Pour the boiling sulfur slowly and
in a thin stream into cold water contained in a dish or
beaker, moving the tube around so that the sulfur may
solidify in a long spiral rod. Examine the product,
especially as to color, hardness, and elasticity. Put it
away in the desk and examine it from time to time for
a week or so. What changes take place ?
(c) Fill a combustion cup with sulfur, set it on fire,
and then put the cup in the bottom of a wide-mouthed
bottle, covering it with a piece of cardboard. When
the sulfur ceases to burn, introduce a piece of dry blue
litmus paper. What change of color ? Then put in a
piece of wet blue litmus paper and note result.
(d) Review Experiment 7, I.
98 Elementary Chemistry
NOTE. Experiment ij6 must be performed in the hood.
EXPERIMENT 136. Preparation and Properties of
Hydrogen Sulfid. Place a little ferrous sulfid in a
test tube and add some dilute sulfuric acid. If a gas is
not given off, heat gently. Attach a delivery tube and
collect a small test tube full of the gas by down-
ward displacement (Fig. 44). Ignite the gas and see if
you can detect the odor of burning sulfur. Pass the
gas for several minutes into about 2 C - C - of strong nitric
acid in a test tube. When the inside of the end of the
delivery tube becomes coated with a yellow substance,
substitute a new delivery tube and put it into a second
test tube filled with water. This will yield a solution
of hydrogen sulfid. Rinse out the first delivery tube,
pick out some of the deposit and by means of appropri-
ate tests establish its identity.
Add some of the hydrogen sulfid solution to a little
dilute copper sulfate, CuSO 4 , solution. Result ? Repeat
with lead acetate, Pb(C 2 H 3 O 2 ) 2 , solution; with cad-
mium sulfate, CdSO 4 , solution ; with potassium perman-
ganate (KMnO 4 ) solution, bromin water, and chlorin
water. What is the result in each case ?
If copper, lead, cadmium, and sulfur are all bivalent
elements, what are the formulas of the products ? Write
the equations for the reactions. Repeat these tests,
delivering the hydrogen sulfid gas directly into the
solutions of the salts.
EXPERIMENT 137. Preparation of Sulfur Dioxid.
(a) By the burning of sulfur. Review Experi-
ment 2.
(b) By the decomposition of sulfuric acid by copper.
Put about 10^- of copper in a flask provided with a
cork and delivery tube with interposed "safety bottle"
(Fig. 55), and add about 40 c - c - of strong sulfuric acid.
Heat the flask cautiously, removing the flame when the
Experiments 99
effervescence may become too brisk, and collect two
receivers full by downward displacement. Cover the
bottles well and reserve for use in Experiment 138.
Let the gas pass into a beaker half full of water for a
few minutes, so as to prepare a solution of sulfur dioxid
(sulfurous acid).
(c) By t/ie action of dilute sulfuric acid on sodium
sulfite. Put a layer of sodium sulfite nearly a centi-
meter thick in the bottom of a gas generator, barely
cover it with water, and add through the funnel tube
from time to time dilute sulfuric acid so as to keep up a
rapid evolution of gas. Collect t\vo receivers full by
dow r nward displacement, cover them well and reserve
for Experiment 138. Prepare a solution of sulfur dioxid
by passing the gas into some water in a beaker or a
bottle, and save for Experiment 139.
EXPERIMENT 138. Properties of Sulfur Dioxid.
Bleaching Action, Place in a receiver full of sulfur
dioxid a piece of moistened calico, some petals of a red
flower (carnation), cover and allow to stand for half an
hour or so. What happens ? Remove the object intro-
duced and place it in a dish containing very dilute sul-
furic acid. What change in color ensues ?
Oxidation by Nitric Acid. Pour a few drops of
strong nitric acid into a receiver filled with sulfur
dioxid, cover and move the receiver around so that its
inside walls may become moistened with the acid.
What visible evidence is there that the nitric acid is
being reduced ? To prove that the sulfur dioxid has
been changed into the trioxid (which dissolves in the
water to form sulfuric acid), rinse out the receiver with
a little water, pour into a test tube and add barium
chlorid solution. The appearance of the white precipi-
tate of barium sulfate indicates the presence of sulfuric
acid.
ioo Elementary Chemistry
EXPERIMENT 139. Properties of Sulfurous Acid.
Test the action of the solution of sulfur dioxicl prepared
in Experiment 137 on litmus paper. Cautiously taste
a drop of it on a stirring rod. Pour some of it into an
evaporating dish, add a few drops of litmus solution or
other indicator, neutralize with sodium hydroxid solu-
tion and evaporate the solution to dryness. How can
you prove that the white residue is the salt, sodium
sulfite, Na 2 SO 3 ?
Add a drop or so of potassium permanganate solu-
tion to a little sulfurous acid in a test tube. Repeat,
using potassium dichromate instead of permanganate.
Compare results.
EXPERIMENT 140. Properties of Sulfuric Acid.
Decomposition by /teat : Place not more than one drop
of strong sulfuric acid in a porcelain dish and heat.
Heat generated on mixing with water : Pour a few
drops of strong sulfuric acid into a test tube half filled
with water. Action of organic substances: Try the
action successively of a few drops of strong sulfuric acid
on (a) a splinter of wood, (/;) a piece of paper, (c) a
piece of colored cloth, (d) a little sugar, (c) a little
starch. It may be necessary to heat gently in the last
two cases.
PHOSPHORUS
CAUTION. All experiments with phosphorus
should be carried out with the utmost caution, as
the ready inflammability of the yellow modification
of the element makes such experiments dangerous.
The waxy modification should never be touched
with the fingers and should be handled and cut
UNDER WATER. At the conclusion of an
experiment all bits of phosphorus left over should
be carefully collected and burned.
Experiments 101
EXPERIMENT 141. Physical Properties of Phos-
phorus. Examine both red and yellow phosphorus,
carefully noting their chief characteristics. Put a piece
(3 mm.) of yellow phosphorus in a small dry test tube
and add about 3 c - c - of carbon bisulfid.
CAUTION. Be sure that no flames are near.
Shake carefully for a minute or so. Pour the solu-
tion, every bit of if, upon two or three pieces of filter
paper laid on a ring of a retort stand and set the stand
back out of the way.
While waiting for the carbon bisulfid to evaporate,
put a pinch of red phosphorus in a small dry test tube,
add about 3 c - c - of carbon bisulfid, shake for a minute or
so, filter through a dry filter paper, catch the filtrate in
a watch glass, and allow to evaporate (in the hood). Is
red phosphorus soluble in carbon bisulfid ? What hap-
pens to the solution of yellow phosphorus poured on
the filter paper? How do you account for the result?
EXPERIMENT 142. Conversion of Red Phosphorus
into Yellow Phosphorus. Put a pinch of red phos-
phorus in the bottom of a small ignition tube 7 , hold the
tube horizontally with the tongs, and gently heat the
bottom of the tube. When nearly all the red phos-
phorus has disappeared, let the tube cool, then make a
scratch just below the deposit that has collected in the
cooler part of the tube and break the tube. Rub the
deposit with a glass rod or match stick. How do you
know that yellow phosphorus has been formed ? Do
not neglect to heat both parts of the tube to redness so
as to burn up all the phosphorus.
EXPERIMENT 143. Preparation and Properties of
Phosphin. Fill a test tube fitted with a two-hole cork,
through which pass tubes as shown in Fig. 62, about
one-fourth full with sodium hydroxid solution, and put
into it a piece (4 *) of phosphorus. Connect the tube
102
Elementary Chemistry
which dips into the soda solution with the gas supply
and pass through the apparatus ordinary illuminating
gas until the air is expelled. How can you prove this
to be the case? Shut off the gas and gently heat the
contents of the test
tube, keeping the end
of the delivery tube
below water in a dish.
How do you account
for the rings of smoke
that appear ?
EXPERIMENT 144.
Preparation of Me-
taphosphoric Acid.
Put a little heap of
red phosphorus on a
piece of asbestos
paper (or in a porce-
lain crucible) set in a
crockery plate, ignite
the phosphorus and
invert over it a perfectly dry wide-rnouthed bottle.
When the phosphorus ceases to burn set the bottle
upright. Pour a few drops of cold water on the phos-
phorus pentoxid formed, noting any hissing noise, and
test the solution with blue litmus. Put the solution
into a test tube and add silver nitrate solution. What
is the precipitate formed ?
EXPERIMENT 145. Preparation of Orthophos-
phoric Acid. Put a little (i cm - circle) red phosphorus
in an evaporating dish, cover it with nitric acid, and
heat gently. When the action has ceased, filter, if the
solution is not clear, and evaporate the filtrate on the
water bath. Redissolve the sirup which remains in a
little water. What is its action on blue litmus paper?
FlG. 62 CONVENIENT APPARATUS FOR PRE-
PARING PHOSPHIN
Experimen ts 103
Add silver nitrate solution and note nature of the pre-
cipitate of silver orthophosphate, Ag 3 PO 4 . If the pre-
cipitate is of a dark color, it is evident that some phos-
phorus acid was formed also. In that case it is well
to add silver nitrate solution to a solution of commercial
orthophosphoric acid.
EXPERIMENT 146. Reactions of Phosphates. To
a solution of sodium hydrogen phosphate, Na 2 HPO 4 ,
add some calcium chlorid, CaCl 2 , solution. The pre-
cipitate is secondary calcium phosphate, CaHPO 4 .
Prepare some "magnesia mixture" by mixing a little
ammonia hydroxid and ammonium chlorid with magne-
sium sulfate, and add it to a solution of acid sodium
phosphate. The precipitate is magnesium ammonium
phosphate, (NH 4 )MgPO 4 .
ARSENIC AND ANTIMONY
EXPERIMENT 147. Properties of Arsenic. Note
the physical properties of arsenic. In what respects
does it resemble metals? Heat a small particle of the
element on a porcelain crucible cover, noting particu-
larly any odor.
EXPERIMENT 148. Arsin. {Marsh's Test for Arsenic.)
Generate hydrogen in a generator provided with a long
( 2 5 cm ') glass delivery tube drawn out to a jet. Use
none but chemically pure materials. When the air is
displaced, light the hydrogen at the tip. Heat the glass
tube nearest the generator with a Bunsen flame. If a
deposit appears in the cold part of the tube, the zinc or
sulfuric acid is impure and the experiment should be
discontinued and other materials used. If no subli-
mate appears and the hydrogen burns with colorless or
slightly yellow flame, and leaves no spot on the bottom
of a porcelain dish pressed down upon it an instant,
pour a few drops of an arsenical solution down the
IO4 Elementary Chemistry
funnel tube. Heat the tube and note the appearance
of sublimate and the color of hydrogen flame. Press
the porcelain dish in the flame a moment and add
a couple of drops of sodium hypochlorite solution to
the spot.
Soak pieces of green paper in water and test the
water for arsenic as above.
EXPERIMENT 149. Arsenic Trioxid, Trichlorid,
and Trisulfid. (a) Mix a pinch of arsenic trioxid
with an equal bulk of powdered charcoal, put the
mixture in an ignition tube, and slip down over it a
loosely fitting plug of charcoal. With the tongs hold
the tube in a flame so as to keep the charcoal plug red-
hot while heating the mixture of charcoal and oxid.
What is the nature of the deposit that forms in the
cooler part of the tube ? How can you prove this
deposit to be arsenic ?
(b) Heat carefully a pinch of arsenic trioxid with
sodium hydroxid solution. Sodium arsenite, Na 2 AsO 3 ,
is formed.
(c) Boil a little of the trioxid with concentrated
hydrochloric acid. Result ? Dilute with an equal vol-
ume of water. Arsenic trichlorid is formed.
(d) Pass hydrogen sulfid into the solution from (c).
What is the color and appearance of the precipitate ?
Let the precipitate settle, pour off the supernatant
liquid, add some ammonium sulfid to the residue, warm
gently, and shake well for some time.
Soluble ammonium sulfo-arsenite, ( ) 2 AsS 3 , is
formed. To a little of this solution add a slight excess
of hydrochloric acid. What happens ?
EXPERIMENT 150. Arsenic Acid. Boil a little
arsenic with nitric acid for some time, then add just
enough ammonium hydroxid to effect neutralization.
To part of this solution add silver nitrate solution, and
Experiments 105
to another, "magnesia mixture." Compare results with
those obtained in Experiment 146.
EXPERIMENT 151. Properties of Antimony. Note
the physical properties of various samples of antimony
that may be available.
EXPERIMENT 152. Stibin. Follow the directions
in Experiment 148, substituting antimony trichlorid
(Experiment 153) for the arsenical solution.
EXPERIMENT 153. Antimony Trioxid, Trichlorid,
and Trisulfid. (a) Repeat Experiment 149 (a), substi-
tuting antimony trioxid for arsenic trioxid, and com-
pare results.
(b) Boil a little powdered antimony with sodium
hydroxid solution and compare results with those
obtained in Experiment 149 (#).
(c) Place some powdered antimony in a test tube
and add about 3 c - c - of concentrated hydrochloric acid
and one cubic centimeter of concentrated nitric acid.
If a reaction does not start promptly, warm a little, and
let it continue for at least ten minutes. Then dilute
with five times its bulk of water and, if the solution is
not clear, filter it. Pass hydrogen sulfid into the solu-
tion of antimony trichlorid thus prepared. If a precip-
itate does not soon form, add more water. Treat the
precipitate of antimony trisulfid, Sb 2 S 3 , as directed in
Experiment 149 (c) and (d).
(d) Heat some powdered antimony with concen-
trated nitric acid and compare results with those
obtained in Experiment 150.
BISMUTH
EXPERIMENT 154. Properties of Bismuth. Note
the physical properties of bismuth. Try to dissolve a
bit of it in (i) concentrated hydrochloric and (2) con-
centrated nitric acid.
io6 Elementary Chemistry
EXPERIMENT 155. Reactions of Salts of Bismuth.
Place a few small crystals of bismuth nitrate in a test
tube, fill the tube a quarter full with water, and add
small amounts of concentrated hydrochloric acid until
a clear solution is obtained. Pour a few drops of the
solution into water, nearly filling- a test tube. The
white precipitate is bismuth subnitrate, BiONO 3 . Pass
hydrogen sulfid through the rest of the solution. Filter
out the bismuth sulfid, Bi 2 S 3 , and treat with warm yel-
low ammonium sulfid. Filter and acidify the filtrate
with hydrochloric acid. Compare the result with Ex-
periments 149 (d) and 153 (c). How can sulfid of bis-
muth be separated from those of arsenic and antimony ?
MAGNESIUM
EXPERIMENT 156. Properties of Magnesium.
Scrape a piece of magnesium wire or ribbon bright and
note its most obvious physical properties. Grasp one
end of a short piece with tongs and hold it in a Bunsen
flame. What is the product and what are its properties ?
Treat a little magnesium in a test tube with dilute
hydrochloric or sulfuric acid. What gas is evolved?
EXPERIMENT 157. Reactions of Magnesium Salts.
To a little magnesium sulfate solution add sodium or
ammonium carbonate solution. Also add sodium or
ammonium carbonate solution to magnesium chlorid
solution. Compare results. What are the products?
To about 5 c - c - of magnesium sulfate solution add
about one cubic centimeter each of ammonium hydroxid
and ammonium chlorid solution. Then add disodium
hydrogen phosphate solution. The precipitate is mag-
nesium ammonium phosphate (NH 4 )MgPO 4 .
EXPERIMENT 158. Preparation of Magnesium
Sulfate. Place about 20 #- of magnesite in a beaker
or flask and add 30 to 40 c - c - of dilute sulfuric acid. If
Experiments 107
effervescence is not vigorous, heat a little. When solu-
tion is complete, filter and evaporate the filtrate to
crystallization on a water bath. Pour off the mother
liquor from the crystals and dry them by pressing
between folds of filter paper.
EXPERIMENT 159. Preparation and Properties of
Calcium Oxid (Lime) and Hydroxid (Slaked Lime).
Test a piece of marble (12 mm -) with wet red litmus
paper. What reaction does it show ? Support the lump
on a frame of iron wire laid across a ring of a stand,
and heat as hot as possible, using two Bunsen flames,
or, better, a blast lamp. After heating for about fifteen
minutes remove the flames, and as soon as the lump is
cold, test it again with wet red litmus paper. What
change has supervened ?
Place the lump of quicklime in a dish or saucer and
pour water upon it drop by drop as long as it is taken
up readily. Do not .add too much water. Keep the
lump under observation for some time, and note any
changes (heat, volume, appearance).
Put some of this slaked lime in a bottle and fill the
bottle with distilled water. Shake up well, let settle,
and decant the clear liquid into another bottle, and
label it "Lime Water."
EXPERIMENT 160. Some Properties of Several
Calcium Compounds. Review Experiment 67. Place
a piece of old mortar in a test tube, add dilute hydro-
chloric acid, and identify the gas.
Stir up some (5 cm - circle) plaster of Paris with
enough water to make a thick paste. Spread the paste
on a piece of paper and lay on it a coin covered with a
thin coating of vaseline, embedding it slightly in the
paste. (Do not delay to wash out the dish, as the
plaster of Paris is hard to remove after it has set.)
Carefully remove the coin after the plaster has set for
io8 Elementary Chemistry
an hour or more. To about 2 c - c - of a solution of calcium
salt (chloric! or nitrate) add ammonium or sodium car-
bonate solution. Repeat, using ammonium oxalate
solution instead of a carbonate solution.
Try the flame test (Experiment 127) with (i) cal-
cium chlorid and (2) calcium sulfate.
Review Experiment 38 for water of crystallization
of gypsum.
EXPERIMENT 161. Reactions of Strontium and
Barium Salts, (a) To a little strontium chlorid solu-
tion in a test tube add a few drops of ammonium car-
bonate solution. Also ascertain the reaction between
a solution of strontium chlorid and dilute sulfuric acid.
(I?) Test solutions of barium chlorid with ammonium
carbonate and dilute sulfuric acid. Try the flame tests,
using (i) strontium chlorid, (2) strontium nitrate, (3)
barium chlorid, and (4) barium nitrate. Look at the
flames through a spectroscope or through a diffraction
grating, if these instruments are at hand.
BORON AND SILICON
EXPERIMENT 162. Preparation of Boric Acid.
Put about 2$#- (7 cm - circle) of borax in a beaker and
add about ioo c - c - of water. Heat and stir until the
borax is all dissolved ; filter if the solution is not clear.
To the hot solution add enough strong hydrochloric
acid to make it decidedly acid to litmus paper. Allow
the solution to cool and stand for some time. Then
filter off the boric acid crystals which have formed, and
purify them by recrystallization from the smallest pos-
sible amount of boiling water.
EXPERIMENT 163. Characteristic Reaction of
Boron Compounds. Dissolve a pinch of boric acid
in about 2 c - c - of strong alcohol contained in an evapo-
rating dish. Dip a tuft of asbestos into the solution
Experiments 109
and, holding it with tongs, set the alcohol on fire. What
is the color of the name ? Ignite the rest of the solu-
tion in the dish.
EXPERIMENT 164. Borax Bead. Make a small (less
than a millimeter in diameter) loop at the end of a piece
of platinum wire by winding it around the point of a
lead pencil. Heat it and touch it to a small lump (2 **)
of borax. Then heat the borax until a clear, glass-like
bead is obtained in the loop. Bring the hot bead in con-
tact with a minute particle of some cobalt or iron com-
pound and heat in the flame. What color is imparted
to the bead ?
EXPERIMENT 165. Preparation of Magnesium Sil-
icid and of Silicon Hydrid. Mix well on a piece of
paper equal parts (2 cm - circle) of powdered magnesium
and very fine sand, place the mixture in a small test
tube and, grasping it with a test tube holder or paper
and tongs, with its mouth pointing so that any of
the substance which may be projected from the tube
can do no harm, hold it steadily in the tip of a Bunsen
flame. After the completion of the reaction break the
test tube and throw small portions of the product (mag-
nesium silicid) into dilute hydrochloric acid contained in
an evaporating dish or beaker. What takes place ? What
compound of silicon is spontaneously inflammable ?
EXPERIMENT 166. Preparation of Silicic Acids.
To about 5 c - c - of a concentrated solution of " water
glass " (a crude mixture of sodium and potassium sili-
cates) add in small proportions hydrochloric acid until
the mixture is strongly acid to litmus paper. Put a
little of the thick, gelatinous mass (a mixture of ortho-
silicic and metasilicic acids) on a piece of platinum foil,
evaporate to dryness, and heat strongly. Add a drop
of water to the white residue, and test it with litmus
paper. What is the powder ?
no Elementary Chemistry
ZINC
EXPERIMENT 167. Properties of Zinc. Ascertain
the most obvious characteristics of as many different
forms (mossy, granulated, powdered, stick) of zinc as
possible. Review Experiments 18 and 104. In Experi-
ment 1 8 hydrogen and zinc chlorid were formed ; in
Experiment 104 hydrogen and sodium zincate.
EXPERIMENT 168. Reactions of Zinc Salts, (a)
Fill a test tube about a fourth full of zinc sulfate or
chlorid solution and add a drop or two of sodium
hydroxid solution. What is the precipitate formed ?
Now add little by little enough sodium hydroxid solu-
tion to redissolve the precipitate formed at first. The
alkalin solution contains sodium zincate.
(b) Fill a test tube about a third full of zinc sulfate
solution and add a drop of dilute hydrochloric acid.
What is the reaction of the mixture (litmus) ? Pass in
hydrogen sulfid for a few minutes. Result ? No\v
transfer the mixture to a beaker and add half its vol-
ume of ammonium sulfid. The precipitate is zinc sul-
fid. Test with litmus. What must the reaction of a
zinc salt solution be in order that the sulfid may be
precipitated ?
EXPERIMENT 169. Blowpipe Reactions. Heat a
small piece of zinc on charcoal in the oxidizing flame
of a blowpipe. Moisten the incrustation with a drop
of cobalt nitrate solution and heat again in the oxid-
izing flame. Result?
CADMIUM
EXPERIMENT 170. Properties and Reactions.
Examine a piece of the cadmium, and note its most
obvious properties.
Into a dilute solution of cadmium chlorid or sulfate
pass hydrogen sulfid gas. The precipitate which forms
Experiments 1 1 1
is cadmium sulfid, CdS. Make the solution acid by
adding a few drops of hydrochloric acid. Is cadmium
sulfid soluble in dilute hydrochloric acid ?
Wash the precipitate by decantation and add ammo-
nium sulfid solution. Is the precipitate redissolved?
How can cadmium sulfid be distinguished from other
yellow sulfids?
Add sodium hydroxid solution in excess to a solution
of a cadmium salt. Is the hydroxid precipitated solu-
ble in caustic alkali solution?
MERCURY
EXPERIMENT 171. Preparation of Mercury. Put
a little cinnabar near one end of a glass tube (15"*-
long) open at both ends, and heat the glass under the
cinnabar strongly, holding the tube in a slanting posi-
tion and rotating it constantly. What gaseous products
are formed? What is deposited in the cooler part of
the tube ?
Mix a pinch of mercury chlorid with two or three
times its bulk of dry powdered sodium carbonate, and
heat the mixture in an ignition tube. Note the nature
of the sublimate.
EXPERIMENT 172. Mercurous Nitrate. Fill the
rounded end of a test tube nearly full of mercury, add
about 5 c - c - of water, and then about $ c - c - of concentrated
nitric acid. Let the action go on for an hour or so.
In the meantime perform Experiment 173. Pour the
contents of the tube off from any mercury that is left
into a small beaker, dissolve in the least possible amount
of water any crystals which may have formed, rinse out
the tube with about 2O C - C - of water, put the rinse water
into the beaker, and add one or two drops of concen-
trated nitric acid, so as to have a clear solution. Save
the solution for Experiment 174.
H2 Elementary Chemistry
EXPERIMENT 173. Mercuric Nitrate. Dissolve
about half as much mercury as was used in Experiment
172 in about io c - c - of concentrated nitric acid. Dilute
the solution of mercuric nitrate thus formed with an
equal volume of water.
EXPERIMENT 174. Reactions of Mercurous Salts.
To 2 c - c - of mercurous nitrate solution add hydrogen
sulfid. The precipitate is a mixture of mercuric sulfid
and mercury. Add to separate portions of the solu-
tion, hydrochloric acid and potassium iodid solution,
respectively. Add ammonium hydroxid to the precipi-
tate from hydrochloric acid. What are the precipitates ?
Put a strip of zinc and of copper (or copper wire) into
portions of the mercurous nitrate solution. In a few
minutes remove them and rub them dry. What has
happened ? Rub a cent or a dime with a piece of paper'
wet with mercurous nitrate solution.
EXPERIMENT 175. Reactions of Mercuric Salts.
Pass hydrogen sulfid into the mercuric nitrate solution.
The precipitate is mercuric sulfid, HgS. Add to sepa-
rate portions of mercuric nitrate solution, hydrochloric
acid and potassium io^id solution (this drop by drop).
What are the precipitates ?
ALUMINUM
EXPERIMENT 1 76. Properties of Aluminum. Exam-
ine as many different forms of aluminum as are avail-
able, also of its alloys ; note their most prominent
physical features.
EXPERIMENT 177. Action of Acids and Alkalis on
Aluminum. Fill the rounded end of a test tube with
aluminum, add about twice its volume of concentrated
hydrochloric acid, and warm and test the gas evolved.
Repeat, using sodium hydroxid solution (cf. Experi-
ment 27). The solution contains sodium aluminate.
Experiments 113
EXPERIMENT 178. Action of Mordants. Soak a
piece of white cotton cloth in a strong solution of cochi-
neal or indigo for a minute or so ; then wring it out and
dry it. Try to wash out the color, using soap. Dip a
similar piece of cloth in a solution of aluminum acetate
and dry it. Then soak it in the cochineal or indigo
solution and dry it. Try to wash out its color.
EXPERIMENT 179. Alums. Weigh out to a decigram
quantities of aluminum sulfate, A1 2 (SO 4 ) 3 -(- i8H 2 O,
and potassium sulfate, K 2 SO 4 , in the ratio of their
molecular weights, i. e. 770 : 137. Fifteen grams of the
first salt to 3 grams of the last are good working quan-
tities. Dissolve each in the smallest possible quantity
of boiling water in a test tube. Mix the two solutions
hot in an evaporating dish and set aside to cool and crys-
tallize. Note taste and form of crystals,
Mix equal volumes of solutions of aluminum sul-
fate and ammonium sulfate saturated at the boiling
temperature. Set aside to crystallize. The product is
ammonium alum.
NOTE. Large crystals may be obtained by hanging a thread
or string in the solution.
EXPERIMENT 180. Reactions of Aluminum Com-
pounds. Add a dilute solution of sodium carbonate
to a dilute solution of alum. Filter the precipitate and
wash it thoroughly. Transfer to a test tube, cover it
with water, and add -hydrochloric acid. If the precipi-
tate is a carbonate, there will be effervescence. Add
ammonium sulfid solution to a solution of alum. Filter
and wash the precipitate and, placing it in a test tube,
add hydrochloric acid. If the precipitate is a sulfid,
hydrogen sulfid gas will be evolved.
To some aluminum sulfate solution in a test tube
add about one-fifth as much sodium hydroxid. Transfer
114 Elementary Chemistry
about half of the precipitate of aluminum hydroxid,
A1(OH) 3 , thus formed to another test tube, and add
an excess of sodium hydroxid. Sodium aluminate is
formed. Is it soluble ? To the other half of the pre-
cipitate add dilute hydrochloric acid. Compare results
with those obtained for zinc in Experiment 168.
TIN
EXPERIMENT 181. Physical Properties. Examine
a stick of tin and a piece of tin foil, and note the physical
properties of the metal. Bend a stick of tin when held
close to the ear. What information does your sense of
hearing give you in regard to tin ?
EXPERIMENT 182. Crystallization of Tin. Hold-
ing a piece of tinplate by means of tongs, heat it in a
flame until the tin coating commences to melt. Then
immediately plunge it into cold water. Rub it over
with a piece of filter paper wet with dilute aqua regia,
then with paper wet with a solution of a caustic alkali.
Note the crystalline figures brought out by the action
of the solvents.
EXPERIMENT 183. Action of Acids on Tin. Fill
the rounded end of a test tube with granulated tin, and
add enough concentrated hydrochloric acid to fill the
test tube about a sixth full. Heat gently (in the hood)
until effervescence commences and regulate the heat-
ing so as to cause the hydrogen to be given off rapidly.
When the action is about at an end, fill the test tube
full of water, and save the solution of stannous chlorid
thus formed for Experiments 184, 185, and 186. Put a
small piece of tin in a test tube and add a little concen-
trated nitric acid. As soon as the reaction begins set
the tube in a bottle in the hood. The white product is
metastannic acid. Heat a little tin with strong sulfuric
acid in a test tube. Result ?
Experiments 1 1 5
EXPERIMENT 184. Preparation of a Solution of
Stannic Chlorid. Fill a small test tube about a sixth
full of the stannous chlorid solution prepared in Experi-
ment 183, and add a little aqua regia, or add bromin in
small portions until its color ceases to be discharged,
and boil to expel the excess of acid or bromin. What
is the action of the aqua regia or the bromin ? Preserve
the solution for use in Experiment 185.
EXPERIMENT 185. Distinction Between Stannous
and Stannic Salts, (a] To a little of the stannous
chlorid solution prepared in Experiment 183 add a few
drops of mercuric chlorid solution. Note the white
precipitate of mercurous chlorid, HgCl. Add more of
the mercuric solution and heat gently. The gray tinge
imparted to the precipitate is due to mercury resulting
from the reduction of the mercurous chlorid.
(b) Add a few drops of mercuric chlorid solution
to some of the stannic chlorid solution prepared in
Experiment 184. What is the result?
(c) Saturate with hydrogen sulfid (i) a little of the
stannous chlorid solution, and (2) of the stannic chlorid
solution, and compare results.
(it) Neutralize the contents of each of the test
tubes with ammonium hydroxid and add yellow ammo-
nium sulfid. Shake up the mixtures in each case and
compare results.
Take fresh portions of the solutions of stannous and
stannic chlorid, and add to each sodium hydroxid
solution, a drop or two at a time.
EXPERIMENT 186. Replacement of Tin by Zinc.
Fill a test tube about one-fourth full of the stannous
chlorid solution prepared in Experiment 183, and fill up
with water. Put a narrow strip of sheet zinc in this
diluted solution and examine after a little while. What
is the appearance of the zinc ?
9
1 1 6 Elementary Chemistry
EXPERIMENT 187. (Quantitative.'] (Hood.) To
Determine the Equivalent of Tin. Weigh about
5.00^- of tin foil in an evaporating dish. Put most of
it on a piece of paper and moisten what is left in the
dish with strong nitric acid. When the action slackens,
put a little more foil into the dish and then a little
more acid. Use as little acid as possible, but be sure
that all the tin is attacked and that there is no loss of
metal from spattering.
Cautiously evaporate to dryness with free flame, and
finally heat as hot as possible for at least ten minutes.
Weigh when it is cool, and after moistening with the
acid heat again ; continue in this way until the weight
remains practically unchanged.
The product is a compound of oxygen. Taking the equivalent
of oxygen as 7.94, calculate that of tin. If tin is quadrivalent
in this compound, what is its atomic weight ? The specific heat
of tin is 0.056 ; what is its atomic weight as deduced by Dulong
and Petit's Rule ?
LEAD
EXPERIMENT 188. Physical Properties of Lead.
Examine as many different samples of lead as possible.
Cut a piece of lead with a knife and note appearance
of freshly cut surface.
EXPERIMENT 189. Deposition of Lead by Zinc.
Fill a test tube nearly full of a solution of lead acetate
(about 10 per cent) and put in it a narrow strip of
sheet zinc. Examine after an hour or so. Pour off a
little of the solution and test it for zinc.
To remove the lead that may still be present add
dilute sulfuric acid to the solution. As lead sulfate is
not wholly insoluble in water, add an equal bulk of
alcohol, in which the sulfate is quite insoluble. Filter
off the lead sulfate, neutralize the filtrate with ammo-
nium hydroxid, and add ammonium sulfid ; a white pre-
cipitate of zinc sulfid results. In case all the lead has
Experiments 117
not been removed from solution by sulfuric acid, the
precipitate caused by ammonium sulfid will not be
white, but more or less of a blackish color, depending
tipon the amount of lead sulfid also precipitated. Hy-
drogen sulfid is a better precipitant of lead than sulfuric
acid, and it is possible to remove all the lead by its use.
Acidify the solution with hydrochloric acid, pass hydro-
gen sulfid through it, filter, and add ammonium hydroxid
and then ammonium sulfid.
EXPERIMENT 190. Action of Acids on Lead.
Scrape three small pieces of lead bright and clean,
place them in test tubes and cover with (i) nitric, (2)
hydrochloric, and (3) sulfuric acid. If no action takes
place promptly, heat to boiling. Note the nature of
any gaseous products and change in the appearance of
the lead. If the lead dissolves in any of the acids, let
the action continue to completion, pour out the solution
into an evaporating dish, and set aside to crystallize.
EXPERIMENT 191. Preparation and Properties of
Lead Monoxid. Heat on charcoal in the oxidizing
flame of a blowpipe a very small bit of lead, and note
any vapors and incrustation formed on the charcoal.
Examine some litharge as to its physical properties and
test its solubility in nitric, acetic, sulfuric, and hydro-
chloric acids, both cold and hot.
EXPERIMENT 192. Preparation and Properties of
Red Lead. Mix about 2&- (2 cm - circle) of lead mon-
oxid with about 0.5^- (2 cm - circle) of powdered potas-
sium chlorate or nitrate, and heat the mixture in an
iron spoon or dish. Note the physical properties of the
product and compare it with other samples of red lead.
Ascertain in what common acids red lead is soluble.
EXPERIMENT 193. Preparation and Properties of
Lead Dioxid. Place about 2 s- (2 cm - circle) of red lead
in a test tube, add some dilute nitric acid, and heat to
iiS Elementary Chemistry
boiling for several minutes. Filter and wash the brown
residue. Put a little of it in a test tube, add concen-
trated hydrochloric acid, and heat gently. What gas
is evolved ? What other peroxid behaves with hydro-
chloric acid in a similar manner?
EXPERIMENT 194. Reactions of Lead Salts. Put
a little dilute solution of lead nitrate or acetate in six
separate test tubes and add to one of each the follow-
ing reagents, noting the nature of the precipitates :
(1) Hydrogen sulfid.
(2) Hydrochloric acid. Add several times as much
water and heat to boiling. What change ? Cool by
holding test tube in running^ water. What is the nature
of the product ?
(3) Sulfuric acid.
(4) Potassium iodid solution.
(5) Potassium dichromate solution.
(6) Sodium hydroxid solution gradually and in
small portions until in excess.
EXPERIMENT 195. Action of Water on Lead. Fill
a flask half full of water and bubble the breath through
it for some time so as to charge the water with carbon
dioxid. Scrape a piece of lead bright and clean, put it
in the flask, cork, and let stand for a day or so. Then
test portions of the water for lead by Experiment 189.
If no lead is found to be present, let the lead act on the
water for a day or so longer, or evaporate off most of the
water and test again. Bear in mind that the lead which
has dissolved may be so slight that the precipitate of
lead sulfid may be so minute as merely to tinge the
liquid brown.
COPPER
EXPERIMENT 196. Properties of Copper. Examine
as many different forms of copper as are procurable ;
note their most prominent characteristics. File a piece
Experiments 119
of copper wire bright and heat it red hot. What is the
black coating? Compare with Experiments 22 and no.
EXPERIMENT 197. Precipitate of Copper. Hang
a strip of zinc (scraped clean) in a neutral solution of
copper sulfate ; also in another test tube containing
copper sulfate solution suspend an iron nail filed bright.
What soon occurs ?
EXPERIMENT 198. Preparation and Properties of
Cuprous Oxid. Dissolve 2 & of copper sulfate in 30 c - c -
of water and add 10^- of Rochelle salt (sodium potas-
sium tartrate) previously dissolved in 20 c - c - of water.
Warm and filter. To the filtrate add IQC.C. o f a dilute
solution of grape sugar, and then enough sodium
hydroxid solution to dissolve any precipitate, and as
much again, so as to make the solution strongly alka-
lin. Boil gently until a decided change occurs. Filter
off the cuprous oxid, Cu 2 O, formed, dry it, and compare
with cupric oxid, CuO.
EXPERIMENT 199. Reactions of Copper Salts. To
a little copper sulfate add ammonium hydroxid in excess.
Then repeat with sodium hydroxid instead of ammo-
nium hydroxid. Heat a solution of copper sulfate to
boiling and add sodium hydroxid. This precipitate is
cupric oxid, CuO.
Review Experiment 136 for the action of hydrogen
sulfid on solutions of copper salts.
Review Experiment 37 for water of crystallization in
copper sulfate crystals.
Dip a copper or platinum wire into copper sulfate
solution, then take it out and heat it in a Bunsen flame;
note the color imparted.
EXPERIMENT 200. (Quantitative.) To Find the
Equivalent of Copper. Clean some copper foil or
wire with emery paper so that it is bright, and weigh
to centigrams 3^- of it. Place the weighed copper in a
I2O Elementary Chemistry
small flask, barely cover it with water, and add concen-
trated nitric acid in small portions, allowing plenty of
time for the action to cease before adding a fresh por-
tion. When solution is complete, transfer the liquid to
a weighed evaporating dish, being careful not to lose
any, and rinse out the flask two or three times with
^c.c. O f W ater, adding the rinsings to the dish.
Cautiously evaporate to dryncss. The blue com-
pound is copper nitrate, Cu(NO 3 ) 2 , which, when heated
to a high temperature, decomposes into nitric oxid, oxy-
gen, and copper oxid, CuO. Heat for at least ten min-
utes as hot as possible even after the decomposition has
seemed complete and then weigh the copper oxid. Heat
again and so on to constant weight. The equivalent of
oxygen is 7.94; find that of copper. Copper is bivalent
in this compound. What then is its atomic weight ?
SILVER
EXPERIMENT 201. Preparation and Properties of
Silver. I. Fill an evaporating dish a third full of sil-
ver nitrate solution, and introduce a few globules of
mercury. Set the dish aside in a safe place for a couple
of days. The silver will then be found forming little
crystals, usually attached to the mercury. Remove them
with steel forceps and, after washing them well, put
them in a bottle labeled " Silver."
II. Pour concentrated nitric acid over a ten-cent
piece in an evaporating dish or beaker, and when the
action slackens, add more acid. Toward the last, heat
may be applied. Add three or four times its volume of
water and then hydrochloric acid until all the silver is
removed as silver chlorid, AgCl. Let this precipitate
settle and wash by clecantation several times. Then
filter and wash free from an acid reaction. Divide it
into two equal parts with a knife or spatula.
Experiments \ 2 1
Place one part in a dish, cover with dilute sulfuric
acid, and add a piece of zinc. The silver which collects
as a gray powder is to be separated from the zinc,
washed and dried. It is then to be placed in a hollow
excavation in a piece of charcoal and heated with a
blowpipe until it fuses into a globule.
Place the second part in a cavity in a piece of char-
coal, cover it with sodium carbonate, and reduce it with
a blowpipe flame. Scrape the minute globules together
and fuse them together into a single bead.
EXPERIMENT 202. Reactions of Silver Salts, (a)
Add a soluble chlorid solution, such as HC1 or NaCl,
to a solution of silver nitrate. Boil, filter, and expose
the silver chlorid to sunlight. Result ?
(b) Add a potassium bromid solution to a solution
of silver nitrate. Heat to boiling, filter, and separate
the precipitate into two parts. To one add sodium
thiosulfate solution, Na 2 S 2 O 3 . Result? Expose the
other half to light. Result ?
(c) Add potassium iodid solution to silver nitrate
solution. Compare the properties of the precipitate
with those of silver chlorid and bromid obtained in (a)
and (b).
IRON
EXPERIMENT 203. Properties of Iron. Examine
as many different forms as possible of the varieties of
iron, note their most obvious physical properties, and
try the action of a magnet on each. Which becomes
permanently magnetized ? Introduce a pinch of iron
powder into a Bunsen flame. What happens ? Review
Experiments 7, I. (;/*); 25, 27, 28, and 51.
To get "clean" ferrous reactions the ferrous solution
must not be given a chance to oxidize. If the hydro-
chloric acid solution be poured directly from the test
tube while hydrogen is still being evolved, there is no
122 Elementary Chemistry
danger of any ferric chlorid being present. Solutions
of ferrous sulfate prepared from the crystals nearly
always oxidize a little so that the true ferrous reaction
is obscured by the ferric reaction.
EXPERIMENT 204. Reactions of Ferrous Salts.
Fill a test tube about a fifth full of iron (filings or small
brads), add enough dilute hydrochloric acid to fill the
test tube nearly half full, and warm, if necessary, to
start the reaction. By appropriate tests identify the
gas given off. Ferrous chlorid is formed in solution.
(a) As soon as the action has almost ceased, pour a
little of the solution into some sodium or ammonium
hydroxid solution. Note the changes of color in the
precipitate of ferrous hydroxid produced. To what
are they due ?
(l>) Add a little of the ferrous chlorid solution to a
solution of potassium ferricyanid, and note nature of
the precipitate of ferrous ferricyanid (Turnbull's blue).
(<r) Add a third portion of the chlorid to potassium
ferrocyanid solution. Result ?
(d) Add a fourth portion to potassium sulfocya-
nate solution, KCNS. Result ? Save what ferrous
chlorid is left for Experiment 205.
EXPERIMENT 205. Reactions of Ferric Salts. Add
more hydrochloric acid to the iron used in Experiment
204 and, after the reaction has almost ceased, filter the
solution into a beaker and add 2 c - c - of concentrated
nitric acid. Boil for a few minutes and note any change
of color. The solution now contains ferric chlorid as
well as ferric nitrate.
To ascertain whether the conversion of the ferrous
into the ferric state is complete or not, put a few drops
in a test tube and add a little potassium ferrocyanid. If
a blue precipitate is formed, add one cubic centimeter
more nitric acid and boil again. Put a little of this ferric
Experiments
123
solution into each of four test tubes and add the four
reagents used in Experiment 204. Tabulate the results
of Experiments 204 and 205 as follows :
Ferrous
Salt
Ferric
Salt
REAGENT
Precipitate or
Solution
Color
Precipitate or
Solution
Color
NaOH .. .
K 3 Fe(CN) 6 __
K 4 Fe(CN) R
KCNS....
How may a ferrous salt be distinguished from a
ferric ?
EXPERIMENT 206. Oxidation of Ferrous Salts.
Place a clear crystal or so of ferrous sulfate in a test
tube and fill the tube half full of water. Shake the
tube until the crystal has dissolved.
(a] Put half of the solution into another test tube,
add a little hydrochloric acid, warm somewhat, and add
a few crystals of potassium chlorate. Heat to boiling
and test for a ferric and a ferrous salt.
(b) To the rest of the ferrous sulfate solution add
a little sulfuric acid, heat to boiling, then run in drop
by drop an equal volume of concentrated nitric acid
and boil for a few minutes. Test portions of the result-
ing solution for the presence of ferric and ferrous salts.
EXPERIMENT 207. Reduction of Ferric Salts. To
a solution of ferric chlorid add a little hydrochloric
acid and drop in some iron so as to give a good evolu-
tion of hydrogen. Add more acid, if necessary, to keep
up the action for at least a quarter of an hour, then
test a little of the solution for the presence of a ferrous
compound. If the test is not decisive, continue the
reduction until it is ; be sure that hydrogen is given off
copiously.
124 Elementary Chemistry
EXPERIMENT 208. Manufacture of Ink. Mix a
strong solution of ferrous sulfate with a little of a solu-
tion of powdered nutgalls. What is the color of the
mixture ? Does it deepen on standing for a few min-
utes ? Dip a pen into it and see how it writes. To a
small portion of the ink add some oxalic acid solution.
What good method does the result suggest in regard to
removing ink stains ?
EXPERIMENT 209. Borax Bead Test for Iron.
Touch a hot borax bead (Experiment 164) to some iron
compound so that a small portion is taken up by it, and
heat in the oxidizing flame of a blowpipe until the
bead is colored a decided^ yellow. Then heat it in the
reducing flame until it becomes green.
NICKEL
EXPERIMENT 210. Reactions of Nickel Salts.
Make the following tests on a dilute solution of nickel
sulfate :
(a) Add sodium hydroxid solution, a few drops at
first, then an excess, and warm.
(b) Add ammonium sulfid solution and see if the
nickel sulfid precipitated is soluble in hydrochloric acid.
(c) Perform the borax bead test in both the oxi-
dizing and reducing flames.
COBALT
EXPERIMENT 211. Reactions of Cobalt Salts.
Use a dilute solution of cobalt chlorid or nitrate, and
add the reagents directed in Experiment 210.
EXPERIMENT 212. Analysis of a Nickel Coin.
Put a five-cent "nickel" in an evaporating dish, cover
with nitric acid, and warm for a few minutes. Pour
the solution into a beaker and dilute with an equal vol-
ume of water. Add ammonium sulfid solution to this
Experiments 1 2 5
solution until no more precipitate is formed. Filter
(saving- the nitrate), wash the precipitate several times,
pierce a hole in the apex of the filter paper, and wash
the precipitate through with a little nitric acid into
a test tube. Heat until it dissolves. What is the color
of the solution, and the presence of what metal is
indicated by this color ? To a little of the solution add
ammonium hydroxid to alkalinity. What is the effect
on the color of the solution ? What metals do these
tests show to have been in the coin ?
Evaporate the first filtrate nearly to dryness. What
is the color of the concentrated solution ? The salts of
what metal have this color ? Test the solution with a
borax bead. What do you conclude ? What is the
qualitative composition of a nickel coin ?
CHROMIUM AND MANGANESE
EXPERIMENT 213. Reactions of Chromic Salts.
(a] Add a drop or so of sodium hydroxid solution to
2 c - c - of a solution of a chromic salt (chromic chlorid
or chrome alum). The precipitate is chromic hydroxid
Cr(OH) 3 . Add an excess of the sodium hydroxid solu-
tion and shake. Then heat to boiling. Compare results
with those obtained with zinc and aluminum.
(b) Add a little and then an excess of ammonium
sulfid to a chromic solution and compare the result
with that in (a). Does chromium form a sulfid? Do
aluminum and zinc ?
EXPERIMENT 214. Borax Bead Test for Chrom-
ium. Touch a borax bead to a bit of chromium alum
and heat in both oxidizing and reducing flame of a
blowpipe. The green coloration is very characteristic.
EXPERIMENT 215. Reduction of Chromates to
Chromic Compounds. To 10 c - c - of potassium dichro-
inate solution add 2 c.c. each of concentrated hydrochloric
126 Elementary Chemistry
acid and of alcohol, and warm gently. The chromate
is reduced to chromic chlorid and the alcohol is oxi-
dized to aldehyde. Note the green color characteristic
of chromic compounds and the peculiar odor of the
aldehyde.
EXPERIMENT 216. Properties of Chromates. (a)
Examine some crystals of potassium chromate and
potassium dichromate. What is the color of their solu-
tions ?
(b) To a solution of potassium chromate add a
little concentrated hydrochloric acid. The change of
color shows that the chromate has been changed into
the dichromate.
(V) To a solution of potassium dichromate add
potassium hydroxid drop by drop until the color changes
to yellow, an indication of the formation of a chromate.
(d) Place a little potassium dichromate in a test
tube, cover with concentrated hydrochloric acid, and
heat gently. What evidence is there that the acid is
oxidized ? Repeat with potassium chromate.
(e) To a solution of ferrous sulfate add a little
hydrochloric acid and then drop by drop a solution of
potassium dichromate. Test a portion of the solution
for ferric salts by means of potassium sulfocyanid
solution.
EXPERIMENT 217. Reactions of Manganous Salts.
(a) Add ammonium hydroxid to a manganous solution
(sulfate or chlorid). The precipitate is manganous
hydroxid, Mn(OH) 2 .
(b) Add ammonium sulfid to a manganous solution.
The precipitate is manganous sulfid, MnS. Divide it
into two parts and add hydrochloric acid to one and
acetic acid to the other, then add an excess of ammo-
nium hydroxid to each. What are your conclusions
regarding the solubility of manganese sulfid ?
Experiments 127
EXPERIMENT 218. Borax Bead Test for Man-
ganese. Put a little of any manganese compound in
a borax bead and heat it in the oxidizing and in the
reducing flame of a blowpipe ; note the color of the
bead in each case.
EXPERIMENT 219. Oxidation with Potassium Per-
manganate. Mix with a solution of ferrous sulfate a
few drops of sulfuric acid, and add, drop by drop, a
solution of potassium permanganate. How can you
show that the permanganate oxidizes the ferrous to the
ferric salt ? Review Experiment 43.
SOME ORGANIC COMPOUNDS
EXPERIMENT 220. Preparation and Properties of
Aldehydes. Formaldehyde. Put about 4 C - C - of methyl
alcohol in a test tube and set the tube in a vertical
position in a rack or bottle. Make a spiral of copper
wire by winding it around a lead pencil, slip the spiral
off, and, holding it with the tongs, heat it as hot as
possible. Quickly drop the heated spiral into the
methyl alcohol. The pungent odor produced is due to
the formation of formaldehyde vapor.
AcetaldeJiyde. To about 3^- of potassium dichro-
mate solution in a test tube add a little concentrated
hydrochloric acid and a few drops of ethyl alcohol.
Heat gently. What does the change in color of the
mixture indicate ? Acetaldehyde is formed by the oxi-
dation of the alcohol, and the peculiar odor is due to
acetaldehyde vapor which is given off.
EXPERIMENT 221. Preparation and Properties of
Ethyl Acetate. Mix about 2 C - C - of ethyl alcohol with
an equal volume of dilute acetic acid in a test tube, and
add a half dozen or so drops of concentrated sulfuric
acid. Heat to boiling and note the odor of the ethyl
acetate formed.
128 Elementary Chemistry
EXPERIMENT 222. Preparation and Properties of
Soap. Put loc^- 6 "- of a 10 to 12 per cent solution of
sodium hydroxid in an iron or tinned dish. Add either
35^- of lard or 100^- of castor oil, and boil gently for
about half an hour. Then add in small portions about
2$<?- of finely powdered salt, NaCl, and boil a few
minutes after all the salt has been added. When the
mixture is cool remove the soap formed.
What reaction does your soap show when tested by
litmus paper ? Add dilute sulfuric acid to a solution of
part of your soap in distilled water until no more solid
separates out. Remove the mixture of stearic and
palmitic acids thus obtained and note its physical
properties.
Put 2 C - C - of your soap solution into two separate
test tubes, and add to one a little magnesium sulfate
solution and to the other a little calcium sulfate solu-
tion. What occurs in each case, and what takes place
on boiling the mixtures for a minute or so ? Saturate
lime water with carbon dioxid as in Experiment 71
until a clear solution of acid calcium carbonate is
obtained. Add a little to a soap solution and note
what happens both before and after boiling the mixture.
EXPERIMENT 223. Fehling's Test for Sugar. Dis-
solve a little cane sugar in water, add a few drops of
sulfuric acid, and boil gently for about five minutes so
as to change the cane sugar into grape sugar. Mix 2 C - C -
each of copper sulfate, Rochelle salt, and sodium
hydroxid solutions in a test tube and heat to boiling.
Add a few drops of the grape sugar solution and boil
for three minutes. If no decided change occurs, add
more sodium hydroxid and more grape sugar and boil
again. The red substance obtained by the reducing
action of the sugar on the copper sulfate precipitate
obtained is cuprous oxid.
Experiments 1 29
EXPERIMENT 224. Preparation and Properties of
Oxalic Acid. Place 5^"- of cane sugar in an evaporat-
ing dish, and add, in portions of about $ c - c -, 50^- f
concentrated nitric acid previously diluted with a tenth
of its volume of water. As the sugar reduces the nitric
acid with evolution of the red fumes of nitrogen per-
oxid, the operation should be conducted in the hood.
Evaporate on a water bath until the volume of the
liquid is less than lo^-. When the solution cools, crys-
tals of oxalic acid separate out.
Wash these crystals with a little water and note their
physical properties. Do not taste the acid, however, as
it is poisonous.
Dissolve a crystal of potassium permanganate in a
test tube a third full of water, and add half as much
diluted sulfuric acid. Add a few drops of this solution
to a solution of oxalic acid. Note the change in color.
Add a drop of ink to a solution of oxalic acid. Result ?
EXPERIMENT 225. Preparation and Properties of
Nitrobenzene. Pour 15 c - c - of concentrated nitric acid
into a flask (250 c - c -) and add an equal volume of con-
centrated sulfuric acid. Cool the mixture by holding
the flask so that tap water may flow around its sides.
Add, a few drops at a time, io c - c - of benzene, shaking
well and cooling the mixture thoroughly after each
addition. Pour the product into a bottle (1,000 to
1,500 c - c -) previously filled with cold water. The oily
liquid which sinks to the bottom is nitrobenzene.
Wash the nitrobenzene free from acid by running a
current of water into the bottle for some time, decant
as much of the water as possible, and then pour the oil
and the remainder of the water upon a wet filter paper.
When the water has drained off, place a test tube under
the funnel, punch a hole in the apex of the filter paper,
and catch the nitrobenzene.
130 Elementary Chemistry
To remove the water which is mixed with the oil
put a few pieces of fused calcium chlorid in the test
tube and let stand for several hours. Note the physical
properties of the nitrobenzene.
EXPERIMENT 226. Preparation and Properties of
Aniline. Put 10^- of nitrobenzene in a flask (250^-),
add 20 c - c - of water and 15^"- of fine iron filings. Shake
well together and add 2 c - c - of concentrated hydrochloric
acid. Hold the flask in the hand and move it around
in a small Bunsen flame so as to keep the contents well
agitated. If the effervescence becomes too violent
remove the flask from the flame, and, if needs be, cool
it by immersion in water. Continue the heating until
the odor of nitrobenzene has disappeared or is very
faint. If the effervescence ceases, add a little more acid.
Now add enough 10 per cent solution of sodium
hydroxid to make the mixture strongly alkalin (litmus),
shake well, let settle for some time, and then decant
into a bottle. Clean the flask out (using concentrated
hydrochloric acid, if necessary), and decant from the
bottle into the flask. Connect the flask with a con-
denser and distil until the distillate no longer has a
milky appearance. The aniline distils with the steam
and on standing for some time settles out as an almost
colorless oil which is heavier than water. Note its
physical properties.
APPENDIXES
APPENDIX A
QUALITATIVE ANALYSIS
INTRODUCTORY
Qualitative chemical analysis has to do with the operations and
methods which are employed in finding out what elements and
radicals are contained in a substance or mixture of substances.
Qualitative analysis consists mainly of the study of the solu-
bilities of substances. In the usual scheme of analysis the sub-
stance to be analyzed is first brought into solution. A solution of
a known compound (a reagent) is then added to this solution, and
if a precipitate of certain properties is formed, a definite conclusion
may be drawn as to the presence of certain elements or radicals
in the original substance taken. Other known solutions are added
to the filtrate from this precipitate, and from the formation of
additional precipitates and observation of their properties further
conclusions can be drawn as to the composition of the original
substance
The solubilities of certain salts of the commoner metals permit
of their classification into five groups, which are usually given the
name of the reagent which is added to effect the precipitation.
These groups are:
Precipitated as sulfids, PbS,
HgS, CuS, CdS, Bi 2 S 3 ,SnS or
SnS 2 , Sb 2 S 3 , or Sb 2 S 5 , As 2 S 3
or As 2 S 5 , by hydrogen sulfid.
The last three are soluble in
yellow ammonium sulfid, the
others not.
f Lead ]
Mercury
(tc salts)
II. Hydrogen
Sulfid Group
Copper
Cadmium
Bismuth
Tin
Antimony
A
lb
Arsenic
[i]
11
Elementary Chemistry
Aluminum 1
Chromium
III. Ammonium
Sulfid Grout?
Iron
Cobalt
Nickel
Manganese
Zinc
tated as hydroxids, A1(OH) 3 ,
Cr(OH) 3 , Fe(OH) 8 , by am-
monium hydroxid. The last
four are precipitated as sul-
fids, CoS, NiS, MnS, ZnS, by
j ammonium sulfid.
IV. Ammonium
Carbonate
Group
Calcium 1 Precipitated as carbonates,
Strontium CaCO 3 , SrCO 3 , BaCO 3 ,
Barium MgCO 3 (soluble in NH 4 C1),
Magnesium J by ammonium carbonate.
V. Alkali Metals
f Lithium
I Sodium
I Potassium
I Ammonj,um
Not precipitated by any com-
mon reagents.
I. HYDROCHLORIC ACID GROUP
METHOD OF ANALYSIS
Add HC1 a little at a time to the solution as long as a precipi-
tate (ptt.) is formed. Shake up well, filter, and wash twice with a
little cold water. Punch a hole in the apex of the filter paper and
wash the precipitate into a beaker. Boil the water and filter
while hot.
Residue: AgCl, HgCl.
Wash with hot water and
twice pour over it enough
Residue:
Filtrate :
Hg-NH 2 -Cl
and Hg.
AgCl-2NH 8
Acidify with
A black resi-
HNO 3 ; a white
due proves the
ptt. proves the
presence of mer-
presence of
cury.
silver.
Filtrate: PbCl 2
Divide into two portions.
PORTION I. Add K 2 Cr.,O 7 or
K 2 CrO 4 ; a yellow ptt. soluble
in NaOH indicates the pres-
ence of lead.
PORTION II. Add KI ; a yel-
low ptt. soluble in hot water
and recrystallizing in plates
on cooling proves the presence
of lead.
Qualitative Analysis iii
REACTIONS OF SOLUTIONS OF SILVER, LEAD, AND
MERCUROUS SALTS
SILVER
HC1 precipitates AgCl, white, curdy, changing on exposure to
the light from lavender to black ; soluble in NH 4 OH, forming
AgCl 2NH 3 , from which solution HNO 3 reprecipitates AgCl.
LEAD
HC1 precipitates PbCl 2 , white, flocculent, soluble in hot water,
crystallizing in long needles when solution cools.
H 2 SO 4 precipitates PbSO 4 , white.
K 2 Cr 2 O 7 or K 2 CrO 4 precipitates PbCrO 4 , yellow, soluble in
NaOH.
Kl precipitates PbI 2 , yellow, soluble in hot water, from which
when cold it crystallizes in shining plates.
H 2 S precipitates PbS, black, changed by hot and moderately
MERCURY
HC1 precipitates HgCl, white, changed by NH 4 OH into a
black mixture of HgNH,Cl and Hg.
II. HYDROGEN SULFID GROUP
METHOD OF ANALYSIS
Warm the nitrate from the Hydrochloric Acid Group and pass
a current of hydrogen sulfid through it. Make sure that precipi-
tation is complete by filtering a small portion, diluting the
nitrate, and treating it with H 2 S a few minutes. Filter and wash
thoroughly with hot water. Put a small portion of the precipitate
in an evaporating dish ; add a little ammonium polysulfid. If this
precipitate dissolves completely, Division A is absent ; if not,
treat the remainder of the precipitate with ammonium polysulfid
and warm (not boil} for about three minutes with occasional
stirring. Filter while hot and proceed as indicated in table for
Division A.
IV
Elementary Chemistry
DIVISION A
Boil the precipitate in an evaporating dish with a small amount
of a mixture of equal volumes of strong nitric acid and water
until brown fumes cease to be given off freely. Dilute with a
little water and filter.
Filtrate : Lead, Bismuth, Copper, Cadmium Salts.
Add a little strong H 2 SO 4 and evaporate with
care until dense white fumes appear. Add an equal
volume of dilute H 2 SO 4 and filter.
Boil with
a very little
Filtrate :
Residue:
aqua regia.
Bismuth, Copper, Cadmium Salts.
PbS0 4
Filter, boil
the filtrate
Add NH 4 OH until strongly alkalin.
Wash,
until chlo-
A deep blue solution proves^the pres-
warm the
rin is ex-
ence of copper. A white ptt. indicates
bismuth. Filter and wash.
ptt. with
ammonium
pelled, then
add SnCU
acetate
and warm.
Fil
Copper, Ca
If copper is
absent :
trate :
dmium Salts.
If copper is
present :
Precipitate
Bi (OH) a or
basic salt
of bismuth.
and a few
drops of
HC 2 H 3 2
and filter.
To the fil-
A gray or
black ptt.
proves the
presence of
mercury.
Make slight-
ly acid with
Acidify with
dil. HC1 and
Add two
or three
trate add
K 2 Cr0 4 or
dil. HCland
precipitate
drops of
K 2 Cr 2 O 7 .
treat with
with H 2 S.
HC1 to the
A yellow
H 2 S.
Filter and
ptt. in the
ptt. soluble
A yellow
boil the ptt.
funnel and
in NaOH
ptt. proves
the pres-
immediately
with dilute
allow the
filtrate to
proves the
presence of
ence of cad-
H 2 S0 4 . Fil-
drop into a
lead.
mium.
ter, rejecting
beaker of
the residue.
water.
Dilute the
A white
colorless fil-
ptt. proves
trate with an
the pres-
equal volume
ence of bis-
of water and
muth.
treat with
H 2 S.
A yellow
ptt. proves
the presence
of cadmium.
Residue:
Mercuric
Salt.
Qualitative Analysis v
REACTIONS OF SOLUTIONS OF MERCURIC, CUPRIC,
CADMIUM, AND BISMUTH SALTS
MERCURY
II 2 S precipitates HgS, black, insoluble in hot and concentrated
HNO 3 , but changed by prolonged action of that reagent into
Hg(NO 3 ) 2 - 2 HgS, white and insoluble in concentrated HNO 3 .
Both Hg(NO 3 ) 2 * 2 HgS and HgS are changed by aqua regia into
sulfur and HgCl 2 , which is soluble. HgS is insoluble in (NH 4 ) 2 S.
SnCl 2 reduces HgCl 2 to HgCl, white. An excess of SnCl 2
reduces the HgCl more or less to mercury, which gives the HgCl
a darker color.
COPPER
H 2 S precipitates CuS, black, changed by hot and concentrated
HNO 3 into sulfur and Cu(NO 3 ) 2 , which is soluble. CuS is insol-
uble in dilute H 2 SO 4 . CuS is slightly soluble in (NH 4 ) 2 S.
NH 4 OH precipitates light blue basic salts, readily soluble in
excess, producing deep blue solutions of ammonia cupric salts, as
CuSO 2 -4NH 3 .
CADMIUM
H 2 S precipitates CdS, varying in color from light yellow to
orange according to the conditions under which precipitation
takes place; easily soluble in concentrated HC1 or in hot and
dilute H,SO 4 ; changed by hot and concentrated HNO 3 into
sulfur and Cd(NO 3 ) 2 , which is soluble. CdS is insoluble in
(NH 4 ) 2 S.
NH 4 OH precipitates Cd(OH) 2 , white, readily soluble in excess,
producing ammonia cadmium salts, as Cd(NO 3 ) 2 ' 4NH 3 .
BISMUTH
H 2 S precipitates Bi 2 S 3 , dark brown ; changed by hot and con-
centrated HNO 3 into sulfur and Bi(NO 3 ) 3 , which is soluble. Bi 2 S 3
is insoluble in (NH 4 ) 2 S.
H 4 O added in large proportion to solutions of bismuth salts
which do not contain too much acid, precipitates basic salts, as
BiOCl, (BiO) 2 SO 4 , BiONO 3 , etc.
NH 4 OH precipitates Bi(OH) 3 or a basic salt, white ; insoluble
in excess ; soluble in dilute HC1.
Elementary Chemistry
DIVISION B
Slightly acidify the ammonium sulfid solution with HC1. [If
the precipitate is white it is probably only sulfur.] Filter, reject-
ing the filtrate, as it contains no metals, transfer the precipitate
to a beaker, add a little concentrated HC1, heat to boiling for a
few minutes, and filter.
Filtrate: Tin, Antimony salts.
Place a bright iron wire or nail in the
filtrate, warm gently, let stand for fifteen
minutes, and then filter.
Filtrate :
SnCl 2
Add HgCl 2 .
A white ptt. get-
ting gray when
more of HgCl 2
is added and
heat applied,
proves presence
of tin.
Precipitate: Antimony
(in metallic state).
Wash thoroughly and
transfer to a beaker. Dis-
solve in a little cone. HC1
to which a few drops of
cone. HNO 3 has been
added. Evaporate nearly
to dryness ; then add a
large proportion of water.
The formation of a white
ptt. proves the presence of
antimony.
[Proof may be confirmed
by passing H 2 S into solu-
tion with formation of
orange ptt.]
Residue:
Arsenic Sulfids.
Dissolve in hot,
cone. HN0 3 . Add
a little of the solu-
tion to a test tube
nearly half full of a
solution of ammo-
nium molybdate,
and warm gently.
A yellow crystal-
line ptt. proves the
presence of arsenic.
Also try the special
tests.
REACTIONS OF SOLUTIONS OF TIN, ANTIMONY, AND
ARSENIC SALTS
TIN (Stannous)
H 2 S precipitates SnS, dark brown ; soluble in warm concen-
trated HC1 ; soluble in (NH 4 ) 2 S, forming sulfo-stannates, as
(NH 4 ) 2 SnS 3 , from which a dilute acid precipitates SnS 2 , yellow.
HgCl 2 is reduced by SnCl 2 in HC1 solution to HgCl, white;
an excess of SnCl 2 reduces some of the HgCl to mercury, which
imparts a darker color to the precipitate.
TIN (Stannic)
H 2 S precipitates SnS 2 , yellow, from solutions not containing
too much HC1 ; soluble in warm concentrated HC1 ; soluble in
(NH 4 ) 2 S, forming sulfo-stannates, as (NH 4 ) 2 SnS 3 .
Qualitative Analysis vii
ANTIMONY (pus)
H 2 S precipitates Sb 2 S 3 , orange red ; soluble in warm, concen-
trated HC1 ; oxidized by hot, concentrated HNO 3 , forming sulfur
and H 3 SbO 4 , which is soluble. Sb 2 S 3 is soluble in (NH 4 ) 2 S ;
forming sulfo-antimonates, as (NH 4 ) 3 SbS <l , from which dilute
acids precipitate Sb 2 S 5 , orange red.
When SbCl 3 is added to a large proportion of water, SbOCl,
white, is produced, which is changed directly to Sb 2 S 3 when
treated with H 2 S.
ANTIMONY (fc)
H 2 S precipitates Sb 2 S 5 , orange red, and resembling Sb 2 S 3
in its behavior toward most reagents.
ARSENIC (ous)
H 2 S precipitates As 2 S 3 , lemon yellow; almost insoluble in
warm, concentrated HC1 ; oxidized by hot concentrated HNO 3
to H 3 AsO 4 , which is soluble, sulfur being set free. As 2 S 3 is
soluble in (NH 4 ) 2 S, forming sulfo-arsenates, as (NH 4 ) 3 AsS 4 , from
which HC1 precipitates As 2 S 5 .
ARSENIC (tc)
H 2 S precipitates As 2 S 5 , lemon yellow, and resembling As 2 S 3
in its behavior toward most reagents. The precipitation takes
place slowly and is more complete if the solution is warm, when
H 2 S reduces the arsenic solution to the arsenious condition and
As 2 S 3 is precipitated.
(NH 4 ) 2 MoO 4 , ammonium molybdate, added in excess to a
solution of arsenic acid containing HNO 3 precipitates ammonium
arseno-molybdate, yellow. Precipitation is best obtained by
adding the arsenic solution to a small test tube half full of
(NH 4 ) 2 MoO 4 . The mixture should then be warmed, but should
not be heated above 70, lest MoO 3 , white, be precipitated.
III. AMMONIUM SULFID GROUP
METHOD OF ANALYSIS
Add NH 4 OH to slight alkalinity, heat to boiling, then add
(NH 4 ) 2 S in slight excess ; heat again to boiling and allow the
precipitate to settle. Filter and wash thoroughly with hot
water. Without delay treat the precipitate in an evaporating
dish with a mixture of equal volumes of strong HC1 and water,
stirring well. Filter and wash immediately.
Vlll
Elementary Chemistry
Residue:
Nickel, Cobalt Sul-
Filtrate: Iron, Aluminum, Chromium, Zinc,
Manganese Chlorids.
rids.
Expel any H 2 S which may be present by
Test with borax
boiling and divide into two unequal portions.
bead ; blue, cobalt ;
PORTION I. Evaporate the smaller portion
brown, nickel.
to small bulk, add a little chlorin w r ater,
To detect one of
and boil until excess of chlorin is' expelled.
these metals in the
To the cooled solution add KCNS. A red
presence of the other,
color proves the presence of iron.
dissolve the residue
PORTION II. To the larger portion add
in a little aqua regia.
Filter and evaporate
a little cone. HNO 3 and boil. Evaporate
to small bulk. Nearly neutralize with
to small bulk. Heat
to boiling and add
(NH 4 ),CO 3 , and, transferring the solution
to a flask, add five times its volume of sus-
an equal bulk of bro-
min water and then
pended BaCO 3 . Shake the flask vigorously
from time to time for half an hour and then
of NaOH. Boil vig-
filter.
orously and add a
little bromin water
from time to time.
Precipitate:
Filtrate: Zinc,
Wash thoroughly
Chromium, Aluminum,
Manganese Salts.
with boiling water
Iron Hydroxids.
PORTION I. Add
by decantation, filter
and boil the ptt. with
NH 4 OH and NH 4 C1
PORTION I. Fuse on
platinum foil with
Na 2 CO 3 andKNO 3 . A
HC 2 H 3 O 2 and
then H 2 S . A
white ptt. soluble
and filter.
yellow product indicates
in HC1 proves the
the presence of chro-
presence ot %ittc*
Residue:
Filtrate:
mium. Dissolve in
PORTION II. Put
Cobalt
Nickel.
water and make acid
a very little in an
[Co(OH) 3 ]
Test with
borax
bead.
Treat
withH 2 S
A black
ptt. indi-
with HC 2 H 3 O 2 . A red
ptt. with AgNO 3 and
a yellow ptt. with
Pb(C 2 H 3 O 2 ) 2 proves
the presence of chro-
evaporating dish,
add 1 cubic centi-
meter of cone.
H 2 SO 4 and heat
until dense white
cates the
mium.
fumes appear.
presence
PORTION II. Add an
Transfer the cooled
of nickel.
equal bulk of solid
contents of the
v^onnrm
Na 2 CO 3 , half as much
dish to a test tube
with bo-
TO V Vlf^Q (\
Ba(OH) 2 , and 5 cubic
half full of H 2 S0 4 ,
I tiX IJt-cUl.
centimeters of water.
add PbO 2 , heat to
Boil two or three min-
boiling and allow
utes. Filter, and to the
to stand until sus-
filtrate add NH 4 C1 and
pended matter set-
boil for some time. A
tles. A red or
white ptt. , best seen
purple colored so-
against a dark back-
lution proves the
ground, proves the
presence of man-
presence of aluminum.
ganese.
Qualitative Analysis ix
REACTIONS OF SOLUTIONS OF NICKEL, COBALT, IRON,
MANGANESE, ZINC, ALUMINUM, AND
CHROMIUM SALTS
NICKEL
NH 4 OH in small proportion precipitates Ni(OH) 2 , green; if
in excess, greenish blue basic salts. The precipitates are soluble
in NH 4 OH in the presence of ammonium salts. Both solutions
and precipitates are changed by (NH 4 ) 2 S into NiS, black.
KOH or NaOH precipitates Ni(OH) 2 , green ; insoluble in
excess. Ni(OH) 2 is oxidized by boiling with bromin water and
NaOH to Ni(OH) 3 , black ; when this is boiled with NH 4 OH and
NH 4 C1 it dissolves.
(NH 4 ) 2 S precipitates from neutral or alkalin solutions NiS,
black; somewhat soluble in excess of (NH 4 ) 2 S, more readily in
the presence of NH 4 OH, forming a dark brown .solution from
which NiS is reprecipitated if the solvent is removed by boiling.
NiS is insoluble in cold and not very dilute HC1 ; it is changed
by aqua regia to free sulfur and NiCl 2 , which dissolves. NiS is
oxidized by the oxygen of the air to NiSO 4 .
A borax bead is colored brown when fused with a compound
of nickel.
COBALT
NH 4 OH precipitates blue basic salts ; easily soluble in NH 4 OH
in the presence of ammonium salts. Both precipitate and solution
are changed by (NH.^S into CoS.
KOH or NaOH precipitates from cold solutions a blue basic
salt which, when warmed with the alkali, changes to Co(OH) 2 ,
pink. Co(OH) 2 is oxidized to Co(OH) 3 , black, by boiling with
bromin water and NaOH. The Co(OH) 3 is not affected by boil-
ing with NH 4 OH and NH 4 C1.
(NH 4 ) 2 S precipitates from neutral or alkalin solutions CoS,
black ; insoluble in excess ; practically insoluble in not very dilute
HC1 ; attacked by aqua regia, forming sulfur and CoCl 2 , which
dissolves. CoS is oxidized by the air to CoSO 4 .
A borax bead is colored blue when fused with a compound of
cobalt.
IRON {Ferrous}
NOTE. As ferrous salts oxidize very readily to ferric, it is only
by taking special precautions that a solution of ferrous salt can
x Elementary Chemistry
be kept from oxidizing. The solution of FeSO 4 should be heated
with iron filings and H 2 SO 4 , when the hydrogen will reduce any
ferric salt to the ferrous condition.
NH 4 OH in neutral solutions precipitates incompletely
Fe(OH) 2 , which oxidizes promptly to compounds first green, then
black, and finally reddish brown Fe(OH* 3 . When these precip-
itates are treated with H 2 S they change into FeS, black.
KOH or NaOH precipitates Fe(OH) 2 , white, but oxidizing as
described above.
(NH 4 ) 2 S precipitates FeS, black'; attacked by hot concentrated
HNO 3 , forming sulfur and Fe(NO 3 ) 3 , which dissolves. FeS is
soluble in dilute HC1, and on exposure to moist air oxidizes to
FeSO 4 , and finally to a basic ferric sulfate which is brown.
BaCO 3 , shaken with a cold, neutral, or slightly acid solution of
FeCl 2 , does not precipitate a compound of iron. It is most con-
venient to employ the BaCCXj suspended in water.
KCNS, potassium sulfocyanate, produces no red coloration in
solutions of ferrous salts.
Concentrated HNO 3 , or chlorin water, oxidizes ferrous to ferric
salts very promptly at the boiling temperature.
IRON (Ferric}
NH 4 OH, KOH, or NaOH, precipitates Fe(OH) 3 , reddish brown
and gelatinous ; changed by (NH 4 ) 2 S into FeS, black.
BaCO 3 , when shaken with a cold, neutral, or but slightly acid
solution of a ferric salt, precipitates Fe(OH) 3 or a basic salt.
KCNS, potassium sulfocyanate, in excess, forms with solutions
of ferric salts a deep red complex soluble salt.
H 2 S reduces acid solutions of ferric salts to the ferrous condi-
tion with separation of sulfur.
MANGANESE (pus)
NH 4 OH, KOH, or NaOH, precipitates Mn(OH) 2 , white, oxi-
dized quickly to dark brown compounds. The precipitate is
changed to MnS by (NH 4 ) 2 S.
(NH 4 ) 2 S precipitates MnS, pink, soluble in dilute acids ; when
exposed to the air it turns brown.
BaCO 3 , shaken with a cold, neutral, or slightly acid solution of
MnCl 2 , does not precipitate a compound of manganese.
Fusion with Na 2 CO 3 and KNO 3 oxidizes manganese com-
pounds to green salts of manganic acid, K 2 MnO 4 and Na 2 MnO 4 .
Qualitative Analysis xi
PbO 2 , lead dioxid, boiled with H 2 SO 4 and a little of a man-
ganese compound, oxidizes the latter to permanganic acid,
HMnO 4 , which imparts a pink or purple color to the solution. If
a chlorid or HC1 be present in any considerable quantity it must
be removed by evaporating with concentrated H 2 SO 4 until dense
fumes appear.
ZINC
NH 4 OH produces in neutral solutions a partial precipitation
of Zn(OH) 2 , white and gelatinous ; soluble in ammonium salts
producing double salts ; changed by (NH 4 ),S into ZnS.
H 2 S precipitates ZnS, white, incompletely from neutral solu-
tions of zinc salts of the inorganic acids ; it is soluble in most
dilute acids, but is only slightly soluble in acetic acid, and
wholly insoluble in a solution containing an alkalin acetate, as
NaC 2 H 3 O 2 .
(NH 4 ) 2 S precipitates ZnS, white.
BaCO 3 , when shaken with a cold, neutral, or but slightly acid
solution of ZnCl 2 , does not precipitate any compound of zinc.
ALUMINUM
NH 4 OH precipitates A1(OH) 3 , white, gelatinous; somewhat
soluble in excess, the A1(OH) 3 being reprecipitated by heat.
(NH 4 ) 2 S precipitates A1(OH) 3 , as the sulfid is decomposed by
water.
BaCO 3 , when shaken with a cold, neutral, or slightly acid solu-
tion of A1C1 3 , precipitates A1(OH) 3 or basic carbonates.
CHROMIUM
NH 4 OH precipitates Cr(OH) 3 , green, gelatinous, difficultly
soluble in excess and reprecipitated by boiling.
(NH 4 ) 2 S precipitates Cr(OH) 3 .
BaCO 3 , when shaken with a cold, neutral, or but slightly acid
solution of CrCl 3 , precipitates Cr(OH) 3 or basic carbonates.
Fusion with KNO 3 and Na 2 CO 3 oxidizes chromium compounds
to K 2 CrO 4 and Na 2 CrO 4 , yellow. If the fused mass is dissolved
in water and the solution acidified with acetic acid, the addition
of lead acetate precipitates PbCrO 4 , yellow.
Xll
Elementary Chemistry
IV. AMMONIUM CARBONATE GROUP
(The Alkalin Earth Metals]
METHOD OF ANALYSIS
To the solution add NH 4 C1, NH 4 OH, and then (NH 4 ) 2 CO 3 .
Warm, and if a precipitate appears, filter and wash.
Precipitate: BaCO 3 , SrCO 3 , CaCO 3
Filtrate :
Pour small portions of warm acetic acid upon the
Mg. salt.
ptt., avoiding an excess, until it is dissolved. To a
AddNH 4 OH
small portion of the solution add K 2 Cr 2 O 7 , and if a
and
ptt. appears add K 2 Cr 2 O 7 to all of the solution, and
Na 2 HPO 4 .
warm and filter.
R u'b the
Precipitate :
Filtrate :
inner surface
of the test
BaCrO 4
Sr(C 2 H 3 2 ) 2 , Ca(C 2 H 3 2 ) 2
tube with a
glass rod. A
Dissolve in
HC1, warm
Make alkalin with NH 4 OH, add
(NH 4 ) 2 CO 3 and warm. Filter the
crystalline
ptt. proves
the solution
ptt. (if none appears, Sr and Ca are
the presence
and add a
absent), wash thoroughly, and dis-
of magne-
few drops of
solve on the filter with the least
sium.
H 2 S0 4 . A
possible quantity of HC1. Evaporate
white ptt.
just to dryness, dissolve in a little
(which, how-
water, filter if not clear, and evapo-
ever, may
rate to small bulk. Divide into two
appear yel-
portions.
low from the
K 2 Cr 2 O 7 in
the solution)
PORTION I
PORTION II
proves the
SrCl 2
CaCl 2
presence of
Add a little
Add a little
barium.
CaSO 4 , heat to
K 2 SO 4 and heat to
boiling, and if
boiling. If a ptt.
no ptt. appears
forms, filter it off
at once let stand
and to the filtrate
for at least ten
add NH 4 OH till
minutes. A fine
alkalin, then
white ptt. proves
(NH 4 ) 2 C 2 O 4 and
the presence of
warm. A white
strontium.
ptt. proves the
presence of cal-
cium.
Qualitative Analysis xiii
REACTIONS OF SOLUTIONS OF BARIUM, STRONTIUM,
CALCIUM, AND MAGNESIUM SALTS
BARIUM
Na 2 CO 3 or (NH 4 ) CO 3 precipitates from neutral or alkalin
solutions BaCO 3 , white, flocculent at first, but becoming crystal-
line when gently warmed. BaCO 3 is very slightly soluble in
NH 4 C1; freely soluble in HC1 and acetic acid, HC 2 H 3 O 2 , with
effervescence.
H 2 SO 5 precipitates BaSO 4 , white, practically insoluble in
water, acids, or alkalis.
Na 2 CO 3 or(NH 4 ),CO 3 precipitates SrCO 3 , resembling BaCO 3 .
STRONTIUM
H 2 SO 4 precipitates SrSO 4 . Calcium sulfate, although but
slightly soluble in water, is more soluble than SrSO 4 , so that
CaSO 4 will precipitate SrSO 4 from a concentrated solution of a
strontium salt. Precipitation is more complete when the mixture
is warmed or when a concentrated solution of K 2 SO 4 is used
instead of the CaSO 4 .
K 2 CrO 4 or K 2 Cr 2 O 7 does not precipitate SrCrO 4 from dilute
solutions acidified with HC 2 H 3 O 2 .
CALCIUM
Na 2 CO 3 or(NH 4 ) 2 CO 3 precipitates CaCO 3 , resembling BaCO 3 .
K 2 CrO 4 or K 2 Cr 2 O 7 produces no precipitate in dilute solutions
acidified with HC 2 H 3 O 2 , since CaCrO 4 is soluble in both water
and HC 2 H 3 O 2 .
(NH 4 ) 2 C 2 6 4 precipitates CaC 2 O 4 , white, crystalline.
H 2 SO 4 or a soluble sulfate, as K 2 SO 4 , precipitates CaSO 4 only
from concentrated solutions, and then but partially.
MAGNESIUM
NH 4 OH precipitates from neutral solutions containing no
ammonium salts one-half of the magnesium as Mg(OH) 2 . The
other half unites with the ammonium salt which is formed to
produce double salts, such as MgCl 2 2NH 4 C1. These double
salts are soluble in water and not precipitated by NH 4 OH or
(NH 4 ) 2 CO 3 . The object of adding NH 4 C1 in the analysis is to
form the double salt and thus prevent the precipitation of the
magnesium.
XIV
Elementary Chemistry
Na 2 HPO 4 or NaNH 4 HPO 4 precipitates from solutions of
double salts, such as MgCl./ 2 NH 4 C1, in the presence of NH 4 OH,
MgNH 4 PO 4 , white and crystalline. Crystallization may be
hastened by stirring the solution with a glass rod.
V, THE ALKALI METALS: AMMONIUM, SODIUM,
POTASSIUM
METHOD OF ANALYSIS
Ammonia. Put a little of the original substance in a small
beaker and add NaOH. Cover the beaker with a watch glass, on
the under side of which is placed a moistened piece of red litmus
paper. Heat gently, but not to boiling. If the litmus paper
turns blue the presence of ammonia is proved.
Sodium and Potassium. Evaporate the filtrate from the
ammonium carbonate group to dryness and heat until no more
fumes of ammonium salts are given off. Divide the residue into
two portions.
PORTION I. Sodium, Potas-
sium Salts.
Moisten a small portion with
HC1, slip a clean platinum wire
into it and introduce into the
Bunsen flame. A yellow flame
proves the presence of sodium ;
a violet flame proves the pres-
ence of potassium.
If sodium is present, view
the flame through a blue glass,
whereby the yellow rays are
cut off, but the violet allowed
to pass.
PORTION II. Potassium, So-
dium Salts.
Dissolve in least possible
amount of water and divide solu-
tion into two portions.
PORTION I.
Add platinum
chlorid solution
and keep under
observation for
some time. A
yellow ptt.
proves pres-
ence of potas-
sium.
PORTION II.
Add picric acid
solution. A yel-
low ptt. indi-
cates presence
of potassium.
REACTIONS OF SOLUTIONS OF AMMONIUM, POTASSIUM,
AND vSoDiUM SALTS
When
AMMONIA
KOH or NaOH when warmed with an ammonium salt liberates
ammonia, which turns moist red litmus paper blue.
any ammonium salts are heated they break up into
Qualitative Analysis xv
volatile constituents so that through heat ammonia may be sepa-
rated from non-volatile substances.
SODIUM
Flame test. A sodium salt introduced into a Bunsen flame on
a platinum wire colors it an intense yellow.
POTASSIUM
Platinum chlorid, PtCl 4 , produces a yellow precipitate.
Picric acid produces a yellow precipitate.
Flame test. A potassium salt introduced into a Bunsen flame
on a platinum wire colors it violet. As this color is marked by
even a very small proportion of sodium, if that element is present,
the flame should be observed through blue glass, which absorbs
the yellow light.
DETECTION OF ACIDS
I. BARIUM CHLORID GROUP
Sulfuric acid, H.,SO 4 , precipitates BaSO 4 , white, insoluble in
HC1.
In neutral solution phosphoric acid, H 3 PO 4 , precipitates
Ba 3 PO 4 , white, soluble in HC1.
Sulfurous acid, H 2 SO 3 , precipitates BaSO 3 , white, soluble in
HC1 with evolution of SO., (odor).
II. SILVER NITRATE GROUP
Hydrochloric acid, HC1, precipitates AgCl ; white curds very
soluble in NH 4 OH.
Hydrobromic acid, HBr, precipitates AgBr, pale yellow,
slowly soluble in NH 4 OH.
Hydriodic acid, HI, precipitates Agl, yellow, very slightly
soluble in NH 4 OH.
III. SPECIAL TESTS FOR SOME COMMON ACIDS
Carbonates. Most carbonates give up their carbon dioxid
when acted upon by HC1 or HNO 3 . (See Experiment 67.)
Sulfids. HC1 evolves H 2 S readily from the sulfids of the
alkali and alkalin earth metals, and from sulfids of magnesium,
manganese, zinc, and iron; less readily from those of lead, bis-
muth, cadmium, antimony, tin, nickel, and cobalt ; from other
sulfids with difficulty or not at all.
x r /i Elementary Chemistry
H 2 S blackens filter paper moistened with lead acetate solution.
A sulfid, when fused with a small piece of solid NaOH on a
crucible cover, forms Na 2 S, which, when moistened and placed on
a silver coin, gives a black stain of Ag 2 S.
Ace fates. Concentrated H.,SO 4 when warmed with an acetate
liberates acetic acid, HC 2 H 3 O 2 , recognizable odor. (See also
ethyl acetate, Experiment 221.)
In neutral solution FeCl gives a dark red color to a solution
of an acetate.
Nitrates. (See Experiment 129.)
APPENDIX B
THE METRIC SYSTEM OF WEIGHTS AND
MEASURES
The metric system of weights and measures is
employed in the affairs of everyday life in most of the
countries of continental Europe, and is almost exclu-
sively used in science.
The fundamental unit is the meter, which is a unit
of length a little over a yard long. The other units of
length are derived from the meter by successively
multiplying and dividing it by ten. The names of
these derived units are indicated by prefixes. Thus,
the multiple prefixes are the Greek words for ten,
deca-, hundred, hecto-, and thousand, kilo-, and the sub-
multiple prefixes are the Latin words for ten, deci-,
hundred, centi-, and thousand, milli-.
The unit of weight or mass is the gram, which is the
weight of a cubic centimeter of water at 4. The same
prefixes as are given above are used in expressing the
names for the multiples and sub-multiples of the gram.
The unit of volume is the liter, which is the volume
occupied by 1,000 cubic centimeters (one cubic deci-
meter of water); 1,000 grams (one kilogram) of water
occupies one liter at 4.
In this system fractions must always be expressed
decimally, and only one unit should be employed in
designating a quantity measured. Thus, the fractions
%, y$, ^A, etc., are written 0.5, 0.33, 0.75, and so on.
Also the weight of an object is not given as nine grams,
four decigrams, and six centigrams, even when abbre-
viated into 9^-, 4^-, and 6 ^-, but should be written 9.46^-.
[ xvii ]
3h
XV111
Elementary Chemistry
The relations between the units, multiples, and sub-
multiples of the metric system are shown in the
TABLE OF THE METRIC SYSTEM
Length
Weight
Volume
Notation
Kilometer
Kilogram
Kiloliter
IOOO.
Hectometer
Hectogram
Hectoliter
IOO.
Decameter _.
Decagram
Decaliter
10.
METER
GRAM
LITER
i .
Decimeter
Decigram
Deciliter
O. I
Centimeter
Centigram _
Centiliter . .
O.OI
Millimeter
Milligram..
Milliliter
O.OOI
It is evident from the table that 10 millimeters equal
one centimeter, 10 centimeters equal one decimeter, 10
decimeters equal one meter, 10 meters equal one hecto-
meter, and 10 hectometers equal one kilometer. Anal-
ogous statements are true for the units of weight and
volume.
The abbreviations most often used in this book are :
cm. f or centimeter ; c - c - for cubic centimeter ; L for liter ;
and # for gram.
The relations of the weights and measures of the
metric system to the weights and measures commonly
used in English-speaking countries are shown by the
TABLE OF METRIC EQUIVALENTS
One meter
39-37
inches
One kilometer
0.62
mile
One centimeter
o 39
inch
One liter
.
i 06
liquid, quart
One gram
15-43
grains
One kilogram
2 2
pounds (Avoir.)
One metric ton
2204
pounds
One inch _
2.54
centimeters
One mile
1.61
kilometers
One cubic inch
16.39
cubic centimeters
One liquid quart
0-95
liter
One pound (Avoir.)
0-45
kilogram
One ounce
28.35
grams
Onfi o-rflin fAnoth "k
__
o . 06/18
eram
APPENDIX C
100
INSTRUMENTS FOR WEIGHING AND
MEASURING
The Thermometer. The thermometer is an in-
strument for measuring temperatures. Its action de-
pends upon the fact that liquids expand
when heated, and contract when cooled.
The liquids in common use are mercury
or alcohol ; water is not suitable, as it
freezes at too high a temperature.
Chemical thermometers (Fig. a) consist
of a glass tube with minute bore, which
is blown out into a bulb at the end. The
bulb is almost invariably made cylindri-
cal in shape so that the thermometer
may be thrust through a cork closing a
flask, test tube, or bottle, the tempera-
ture of the interior of which is to be
found. Details as to the making of ther-
mometers cannot be gone into here, but
brief mention may be made of the
method employed in graduating the
instrument.
The bulb is placed in a dish filled
with melting ice, and the position of the
liquid in the stem marked on the glass.
The instrument is then placed in steam
issuing from water which is kept briskly
boiling under a pressure of one atmos-
phere. The liquid expands much more than does the
glass and rises in the stem. This new position is also
[xix]
Fig. a
THERMOMETERS
XX
Elementary Chemistry
marked on the glass. The portion of the stem between
the points thus fixed is divided into a certain number of
equal parts, the number depending" upon what scale is
adopted. The stem above and below these fixed points
is likewise divided into parts which
are equal to those between the two
fixed points.
In the Centigrade scale, which
is in general use in continental
Europe, and in almost exclusive
use among scientists, the interval
between the temperature of melt-
ing ice and boiling water is divided
into 100 equal parts ; the lower tem-
perature is set at o and the higher
at 100. The Centigrade scale alone
is employed in this book.
In the Fahrenheit sca/e, which is
in general use in English-speaking
countries, the interval between the
fixed points is divided into 180
equal parts, and the temperature of
melting ice is set at 32 and that of
boiling water at 212.
The value of a Centigrade degree
is 1.8 times that of a Fahrenheit de-
gree, and 32 Fahrenheit marks the
same temperature as o Centigrade.
To convert degrees C. into de-
grees F., multiply by 1.8 and add 32. To convert degrees
F. into degrees C., subtract 32 and divide by 1.8.
The Barometer. The barometer is used for meas-
uring the pressure of the atmosphere. In its simplest
form it consists of a straight glass tube, about a meter
long and closed at one end. This is completely filled
Fig. & A SIMPLE
BAROMETER
Instruments for Weighing and Measuring xxi
with mercury, which is boiled in the tube in order to
drive out every trace of air or moisture, and its open
end then placed under the surface of mercury in a dish
(Fig. b). The mercury falls in the tube to a height of
about f j6 cm -. The liquid does not all run out of the tube
because the atmosphere pressing down upon the mer-
cury in the dish pushes it up until the weight of liquid
in the tube exactly balances the pressure of the atmos-
phere. If for any cause the pressure of the atmosphere
Fig. C A TRIP BALANCE
becomes greater, it will push the mercury higher up in
the tube ; and in a similar fashion, if the atmospheric
pressure becomes less, it cannot support so long a column,
and accordingly the liquid in the tube falls somewhat.
The Balance. The balance serves to find the
weight of an object. When the weight is to be ascer-
tained only to tenths of grams, the form of balance
known as the "trip " (Fig. c] is excellent. The weights
accompanying need have no pieces less than 5 f- t as the
beam and sliding weight in the front permit of the
weighing to tenths of grams up to 5 s-.
XX11
Elementary Chemistry
In the quantitative work of this book, a balance
weighing to hundredths of grams at least is required.
Balances sensi-
tive to a milli-
gram are even
better, but are
much more ex-
pensive and must
be enclosed in a
glass case to pre-
vent currents of
air from making
them work too
erratically. Either
an equal-armed
balance (Fig. d] or an unequal-armed one (Fig. e) may
be used. Of the former there are numerous excellent
makes on the market. They require the use of a box of
weights contain-
ing tenths and
hundredths of
grams.
The form of
balance in Fig. e
was devised by
the author for the
quantitative work
of the elementary
chemistry labor-
atory. Its advan-
tages are ease in
moving about,
rapidity of weigh-
ing, and " non-losableness " of the weights, which are
rings moving along the beam.
Fig. e UNEQUAL-ARMED BALANCE
Instruments for Weighing and Measuring xxiii
RULES TO BE OBSERVED IN WEIGHING
1. Always leave the balance and weight
in a clean and usable condition.
2. Never handle Hie vv eights with the
fingers ; use forceps.
3. Do not weigh anything but
metals (mercury and sodium ex-
cepted) en the bare scale pan.
Liquids should be weighed in a
dish or a beaker, the weight of
which has already been found.
Solids should be placed on a
piece of paper creased twice at so c - c -
right angles so as to sink in
a little at the center (Fig. c).
Graduated Vessels. For measuring
rather large volumes of liquids graduated
cylinders (Figs. / and g) of
2$o c - c - or 50^- capacity are
used. Volumetric flasks
(Fig. h) are also employed.
For measuring small vol-
umes of liquids pipettes
(Fig. i) and burettes (Fig.
54, page 77) are used. Pip-
ettes are usually graduated
to deliver 5 c - c -, io c - c - t 25^-,
or 50 c - c -. In using a pipette, its tip is
dipped into the liquid, which is then
sucked up nearly to the top by the
mouth, and the upper opening quickly
closed with the finger. By lifting up the
fore finger so as to let air into the upper p . g fc _ VOLU _
part of the pipette the liquid may be METRIC FLASK
Fig. f 250^.
CYLINDER
XXIV
Elementary Chemistry
made to drop out until its level comes even with the
mark on the stem. The definite volume of liquid
thus measured may then be delivered into the
vessel in which it is to be used.
Burettes are usually graduated into tenths of
cubic centimeters and may hold either 25 c - c - or
50 c - c - ; but as sometimes the spaces are divided
into 0.2 c - c -, that is, fifths of a cubic centimeter,
a burette should be carefully examined before it
is used in order that it may be read correctly
according to its scale of division. They are
clamped vertically to a support and rilled by
pouring in the liquid. Enough liquid is allowed
to run out by opening the clamp to drive out all
air in the delivery tube,\and then by noting the
reading of the level of the liquid in the burette,
the required volume may be run out into the
vessel being used.
A convenient stopcock consists of a glass bead
made from a rod a little larger in diameter than
the bore of the bit of rubber tubing attached to
the burette. This bead is
slipped into the rubber
tube between the burette pig. *
and the delivery tip. By PIPETTE
: B squeezing the rubber a little,
a channel is formed between it
and the bead, through which the
liquid in the burette may flow.
The size of this channel can be
regulated with such ease that
the liquid may be delivered
with great nicety.
The surface of liquids which
^cvet glass is curved upward near
Fig. / READING A BURETTE
The correct reading is along. O.
Readings such as A and B must
not be taken
Instruments for Weighing and Measuring xxv
the glass so that in small tubes the surface is concave.
The name of meniscus has been given to this curved
surface. The position of a liquid surface with respect
to a scale is always reckoned at the lowest point in the
meniscus, and the eye should be placed so that a line
passing from it to the tube is perpendicular to the tube
(Fig.y). In the case of liquids which, like mercury, do
not wet glass, the meniscus is convex, and readings are
taken at its highest point.
It is a good plan for the student to determine the
capacity of his test tubes, beakers, and flasks by pouring
water into them from one of the above vessels. Their
volume once determined, no time is lost in ascertaining
what size of beaker, flask, or test tube is to be used in
the experiments ; they may also serye as rough and
ready measuring vessels.
NAME OF
ELEMENT
Aluminum _
Antimony..
Argon
Arsenic
Barium
Bismuth
Boron
Bromin
Cadmium ..
Calcium
Carbon
Chlorin
Chromium _
Cobalt ...'..
Copper
Fluorin
Gold
Hydrogen . .
lodin
Iron
Lead
Lithium
Magnesium
Manganese.
Mercury
Nickel
Nitrogen
Oxygen
Phosphorus .
Platinum
Potassium...
Silicon
Silver
Sodium
Strontium...
Sulfur
Tin ....
Zinc ..
APPENDIX D
TABLE I PHYSICAL CONSTANTS <
Name of Discoverer and
Date of Discovery
Wohler (1827)
Basil Valentine (1460)
Ramsay and Ray leigh__.( 1894)
Albert Magnus (i3th cent.)
Davy .(1808)
Basil Valentine (i5th cent.)
Gay-Lussac and Thenard (1808)
Balard ..(1826)
Stromeyer (1841)
Davy (1808)
Known from earliest times
Scheele ...(1774)
Vauquelin ( 1 797)
Brand (i?35)
Known from earliest times
Moissan (1886)
Known from earliest times
Cavendish (1776)
Courtois (1812)
Known from earliest times
Known from earliest times. .
Liebig and Bussy . , (1830)
Gahn and John ( I 8o7)
Known from earliest times
Cronstedt (1751)
Rutherford _. (1772)
Priestley ( 1 774)
Brand (1674)
Waston... _. (1750)
Davy (1807)
Berzelius (1823)
Known from earliest times
Davy (1807)
Davy (1808)
Known from earliest times
Known from earliest times
1 5th century
[ xxvi ]
TABLES
>OME OF THE ELEMENTS
Atomic Weights
Valence
Melting
Point
Boiling
Point
Specific
Gravity l
H = i
O - ib
Approxi
mate
26 9
19-3
1Q.6
27.1
120.2
TO. 9
27
120
4O
III.
Ill, V
700 (?)
440
-)
1300 (?)
2.67
6. 7 2
J ' V
74-4
.9 y v
75-o
T- W
75
III, V
446-457
Red heat
5-69
36.4
137-4
137
II
Above that
of cast iron
)
3-75
06.9
208.5
208
III, V
268
1700
9.9
10.9
II.
ii
III
In electric
furnace
p
2.6
79-36
79.96
80
I
7-3
63
3.1 (liq.)
ii. 6
112.4
112
II
320
770
8.72
39-8
40.1
40
II
Red heat
p
i. 6-1. 8
(
Diamond 3.5
11.91
12.00
12
IV
p
? \
Graphite 2.2
\
Charcoal 1.5
35-18
35-45
35-5
I
IO2
34
1-33 (liq-)
5i-7
52.1
5 2
II, III
p
p
6-7
58.56
59-o
59
II
1800
p
8.6
63.1
63.6
63-5
I, II
IO5O
?
8.9
18.9
19.
ig
I
?
95 7
197.2
197
III
1030
p
19-3
l.OOO
1.008
I
I
252. 5
i
25.90
126.85
127
I
114
1 20
4-95
55-5
55-9
56
II, III
I TOO
p
7.88
05-35
206.9
207
II, IV
325
p
n-37
6.98
7-03
7
I
1 80
p
o-59
24.18
24.36
24
II
750
1 100
i-75
54.6
55-o
55
TI
7-2
98.5
200
200
j I
-38:9
357
13-59
58-3
58-7
58.5
,i
1600
p
8.9
13-93
14.04
H
III, V
2O3
194
13-93
15.88
16.00
16
II
1825
15.88
30.77
31.0
3i
III, V
44.2
287]
Yellow 1.83
Red 2.21
93 3
194-8
195
IV
2000
p
21-5
38.86
39-15
39
I
62.1
667
4.9
28.2
28 4
28
IV
Above cast
iron
p
2-5
07. 12
107 93
108
I
IOOO
p
10.5
22.88
23-05
23
I
97-6
742
0-97
86.94
87.6
87
II
Red heat
p
2-5
31.83
32.06
32
IIJV.VI
II4-5
448
2.0
18.1
119.0
119
II, IV
227
1600
7-3
64.9
65-4
65
II
420
930
7-i
i Referred to water if the element be in a solid or a liquid state ; to
tydrogen if in a gaseous state.
[ xxvii ]
xxviii Elementary Chemistry
TABLE II TENSION OF WATER VAPOR
15
12 -itnm.
21
20 gfnm.
16
I7.K mm.
2_1 C
222 7#W.
17
14 4//tt.
25
27 >mm.
18
15 ^mm.
26
2Z omm.
10
1 6 3/w.
27
26 t; /#/.
20 .
ij.^mm.
28
28 I w.
21
1 8 ^tnm.
2Q
29 Sim.
ig -jmm.
30
v i.e. mm.
TABLE III SOLUTIONS TO BE PREPARED
The figures in parentheses indicate the number of cubic centi-
meters (if the substance is a liquid) and the number of grams (if
the substance is a solid) that are to be dissolved in water ; the
solution should then be diluted to one liter.
Acetic acid, (140) of 80$ acid.
Alum (any one), (100).
Aluminum chlorid, (TOO).
Aluminum sulfate, (25).
Ammonium carbonate. Dis-
solve 2oo<?"- in a mixture of
100^- of cone. NH 4 OH and
600 c.c. of water, and after solu-
tion is complete dilute to one
liter.
Ammonium chlorid, (100).
Ammonium hydroxid, (250) of
cone. NH 4 OH.
Ammonium molybdate. Dis-
solve $og- of molybdic acid in
a mixture of 100^- of cone.
NH 4 OH and I$QC.C. of water.
Dilute 250^- of cone, nitric
acid with $QQC.C. of water and
pour into first solution slowly
and with constant stirring.
Let stand in a warm place for
48 hours and decant the clear
supernatant solution for use.
Ammonium nitrate, (25).
Ammonium oxalate, (50).
Ammonium polysulfid. Dis-
solve some sulfur in ammo-
nium sulfid solution.
Ammonium sulfid. Pass H 2 S
into one liter of cone. NH 4 OH
to saturation. Then add
750 c.c. cone. NH 4 OH and one
liter of water.
Ammonium sulfocyanid (also
called thiocyanate), (10).
Antimony chlorid. Dissolve
25^- in a mixture of 250^-
of cone. HC1 and 750 c.c. of
water.
Arsenic chlorid. Dissolve 50^-
sodium arsenite, Na 3 AsO 3 ,
in i ,000^- c. of water and add in
small portions cone. HC1 until
further addition occasions no
effervescence.
Barium carbonate. In suspen-
sion in water.
Tables
xxix
Barium chloric! , (60).
Barium hydroxid. Dissolve 50^-
in one liter of hot water, let
stand over night, and filter or
decant. Keep in tightly
stoppered bottle.
Bismuth nitrate, (25). The solu-
tion must contain a little free
nitric acid.
Boric acid, (40). Saturated solu-
tion.
Bromin solution. Dissolve 2^-
of KBr in 250 c.c. of water,
add 6<"- (2 c.c.) of bromin, and
shake until bromin is dis-
solved,
Bromin water. Put 4o<?"-(i3 c.c.)
in a liter of water. Keep bot-
tle tightly stoppered and in
the dark.
Cadmium chlorid, (25).
Calcium chlorid, (25).
Calcium hydroxid, (lime water).
Put some freshly slaked lime
in a bottle, fill bottle with
water, shake, and when solu-
tion is clear, decant and reject
'it, as it may contain some
impurities from the lime.
Fill the bottle with water
again and shake well.
Calcium sulfate. . Prepare satu-
rated solution in same manner
as lime water above.
Chromium chlorid, (25). To
ijoooc-c. of potassium dichro-
mate solution add $oc.c. of
cone. HC1 and 25 c.c. of alco-
hol. Boil for half an hour
gently and, if, after standing
over night, the solution is not
clear green add more alcohol
and boil again.
Chromium sulfate, (30).
Chlorin water. Pass chlorin
gas into water until it smells
strongly of the gas. Better
make small quantities when
needed by adding a little
cone. HC1 to a few crystals of
KC1O 3 in a test tube and as
soon as the gas escapes from
mouth of tube, adding water
to stop reaction.
Cobalt chlorid, (50).
Cobalt nitrate, (35).
Cochineal. Grind a little with
water and dilute to desired
tint.
Copper nitrate, (40).
Copper sulfate, (35).
Disodium hydrogen phosphate,
(120).
Ferric chlorid, (100).
Ferrous sulfate. Dissolve i5o<?"-
of clear crystals in one liter
of water, and add 5 c.c. of cone.
H 2 SO 4 and a few pieces of
iron (tacks or small nails).
Hydrochloric acid, (250) of cone,
acid.
Indigo. Slowly add lotf- of
powdered indigo to 25 c.c. of
fuming sulfuric acid. Let
stand for a day and then add
slowly with constant stirring
to one liter of water.
Lead acetate, (90).
Lead nitrate, (40).
Litmus. Grind a little with
water to a paste and dilute to
desired tint.
XXX
Elementary Chemistry
Magnesium chlorid, (25).
Magnesium sulfate, (100).
Manganous chlorid, (75).
Manganous sulfate, (35).
Mercuric chlorid, (30).
Nessler's Reagent. Dissolve
35^"- of potassium iodid in
100 c.c. of water ; also dissolve
16^"- of mercuric chlorid in
300^-^ of water. Add the
latter solution to the former
slowly with constant stirring
until the precipitate ceases to
be redissolved. Then add a
solution of 65<?"- of potassium
hydroxid in 60 c.c. of water
and filter. Put the solution
into a number of small bottles
and cover the corks with par-
affin. Keep in a cool, dark
place, and when the solution
is needed, do not open more
than one bottle at a time.
Nickel chlorid, (25).
Nickel nitrate, (35).
Nitric acid, (250) of cone. acid.
Phenolphthalein. Dissolve one
gram in IOQC.C. o f alcohol and
dilute with water until a pre-
cipitate begins to form ; then
add enough alcohol to clarify
solution.
Platinum chlorid. Use com-
mercial solution, or, dissolve
scrap platinum in aqua regia,
evaporate nearly to dryness,
and dissolve residue in enough
water to make about 10 per
cent solution.
Potassium bromid, (30).
Potassium chromate, (100).
Potassium chlorid, (50).
Potassium dichromate, (50).
Potassium ferricyanid, (30).
Potassium ferrocyanid, (50).
Potassium hydroxid, (150).
Potassium iodid, (25).
Potassium nitrate, (100).
Potassium sulfate, (100).
Potassium sulfocyanate, (50).
Silver nitrate, (40). Keep in
amber glass bottle.
Sodium acetate, (130).
Sodium ammonium phosphate,
(7o).
Sodium chlorid, (100).
Sodium hydroxid, (175).
Sodium sulfite, (200).
Stannous chlorid. Dissolve
So.?"- in IOQC.C. of hot cone.
HC1 and keep a few pieces of
tin in the solution. Make
only when needed, as it does
not keep well.
Starch paste. Grind about
lotf- to a paste with a little
cold water, then boil with
250 c.c. of water until clear.
Strontium chlorid, (30).
Strontium nitrate, (30).
Sulfuric acid, (250) of cone. acid.
Pour acid in small portions,
with stirring, into the full
amount of water required for
dilution.
Tartar emetic, (100).
Zinc chlorid, (50).
Zinc sulfate, (140).
APPENDIX E
SIGNIFICANT FIGURES AND FORMS OF
RECORD IN QUANTITATIVE WORK
All the figures of a number are called significant
excepting the ciphers at the right of a whole number
and the ciphers at the left of a decimal fraction ; thus,
the significant figures of 30,600 as well as of 0.000306
are 306.
In all measurements one significant figure more than
is known to be correct is kept in the number express-
ing the result of the measurement ; this figure is said
to be the least accurate figure or the doubtful figure of
the number. Thus, suppose the volumes of water dis-
placed from an aspirating bottle in three determinations
of the weight of a liter of oxygen (Experiment 16) were
found to be in each case, 1685 c - c -, 1680 c - c -, and 1689 c - c - ,
the sum of these three numbers is 5054, and their mean
is 1684.666 -f c.c. 9 or 1684.66! c-c; or 1684.67^-. No one
of these is proper, for each assumes a greater accuracy
than we have any warrant for ; moreover, the second is
irrational in its combining a common with a decimal
fraction. The three determinations differ in units'
place ; hence, we are not sure of units' place. We must
accordingly drop the entire decimal part of the average
number ; but as the decimal is greater than 0.5, it is
customary to change the figure 4 in the average to 5, so
that the average is 1685. If the decimal had been less
than 5, it would have been dropped, and the average
would have remained 1684.
[ xxxi ]
xxxii Elementary Chemistry
Again, suppose that in three weighings of a dish the
following results were obtained: 24.^^^-^ 24. 35^-, and
24.32^-. The sum of these numbers is 73.00, and their
average arithmetically may be 24.3333 + or 2 4-33y, but
if the above rules be observed, the average must be
24.33. It i s to be noted that the sum is given as 73.00
and not as 73. By writing the two ciphers in the deci-
mal we indicate that we know that the tenths and hun-
dredths are zero, while the 73 without the ciphers leaves
us in doubt.
Let another illustration emphasize this last point.
Suppose the weight of a vessel be found on a balance
sensitive to a hundredth of a gram, but that neither the
tenths nor the hundredths gram-weights are needed
to secure equilibrium, ilf only the ten- and two-gram
weights are on the pan of the balance, its weight is
written i2.oo<?"- and not just 12^-. The ciphers indicate
the degree of accuracy attained. They mean that the
tenths and hundredths were tried in determining the
weight, but were not needed. By expressing a weight
as 12.00^- you indicate that a balance sensitive to hun-
dredths of grams was used, while 12.0^- would mean
that a balance sensitive only to tenths of grams was
employed.
In the directions for the quantitative experiments
the degree of accuracy is denoted by the number of
decimal places kept in specifying a quantity to be taken.
Thus, in Experiment 46, exactly 2.00^- are specified,
which means that on a balance sensitive to hundredths
of grams, two grams, and not more or less by a hun-
dredth of a gram, are to be taken. In Experiment 16
the directions are to take about 5 & of manganese dioxid.
This quantity may be weighed roughly, that is, to about
a gram, it making no difference if 4^- or 6^- should hap-
pen to be taken. If the amount had been written 5.0 &-,
Significant Figures and Forms of Record xxxiii
it would have been necessary to use a more sensitive
balance and weigh to tenths of grams.
Suppose that it were found that 2.68<^- of oxygen
occupied a volume of 1,871 c - c -, i. e., 1.871 L . Then the
quotient of 2.68 divided by 1.871 gives the weight of one
liter. The question arises : How many figures of the
quotient are to be retained ? It is apparent that if only
weighings to hundredths of grams were made, then
only hundredths should be kept. Accordingly the
quotient is 1.43.
Arithmetical operations on data obtained in quanti-
tative experiments may be much abbreviated, with no
loss in accuracy, by dropping after an operation of mul-
tiplication or division all except the significant figures
in a number.
To illustrate, let us solve the following problem :
Find the reduced volume of 283 c - c - of a gas measured
at 662 >> and 22.
It is to be noted that no one of the three numbers
given has more than three figures ; hence, there are
only three significant figures. Substituting in the for-
mula ( 27), we have
Below are given two calculations of the value of V,
the one to the right retaining all figures after each mul-
tiplication, the one to the left retaining in each product
only three (significant) figures.
283 283
273 273
849
1981
566
77259 77259
3b
xxxiv Elementary Chemistry
773 77259
662 662
4638 463554
4638 463554
5^726 5H45458
2 95 295
760 760
17700 17700
2065 2065
224200 224200
224) 512(228.5 224200) 51145458 (228.1
448 "
_
640 6305
448 4484
1920 18214
I79 2 17936
1280 2785
As is seen, the reduced volumes differ only in the
first decimal place. But as the units are doubtful, the
tenths are not significant. As the tenths in 228.5 i g -5>
the number according to custom is increased to 229. It
is thus manifest that the abbreviated operations give as
good results as the detailed one.
FORMS OF RECORD OF DATA
It always saves time and energy to enter data as soon
as obtained in some approved tabular form. Always
use a note book, never a scrap of paper. Preserve all
the arithmetical work so that, if necessary, it may be
checked up with a second determination. Some forms
of tabular entries are given at the end of the directions
Forms of Record of Data xxxv
for the performance of various experiments. A very
common operation in quantitative work is the fol-
lowing :
A dish or other vessel is weighed, some substance
placed in it, and a second weighing made. The differ-
ence in the weights gives the weight of the substance.
A good form of record for this operation is this :
Wt. of dish, crucible, or test tube + substance = 47. 63^"-
Wt. " _.. _ = 23.42^"-
Wt. of substance = 24. 21^"-
Suppose a substance is being heated to constant
weight in an evaporating dish. A convenient form of
record is the following :
Wt. of dish + substance after heating for 20 min = 47.84^-
Wt. " + " " 10 " more = 47.67^-
Wt. + " 10 " " = 47.63<r-
Wt. " + " " " " 10 " " = 47.63^-
Wt. " = 23. 42 <r-
Wt. of substance = 24. 21^"-
Other similar forms may be readily devised by the
student. It is a good plan to decide upon what form
of record is to be used before commencing a quantita-
tive experiment. The very preparation of a form often
helps wonderfully in keeping track of the steps in an
experiment.
APPENDIX F
LABORATORY EQUIPMENT
The subjoined lists contain the apparatus and the chemicals
required for the experiments in this book. Prices and quantities
have not been given, but the author will be pleased to give infor-
mation to teachers using the book as to the quantities of apparatus
and chemicals used by his own classes. Prices may be obtained
from any of the dealers in chemical supplies.
LIST A
i
INDIVIDUAL APPARATUS
This list comprises the pieces of apparatus constantly used by
a single student, who should be provided with each piece.
Iron tongs.
Platinum wire.
Blowpipe.
Iron forceps.
'Triangular file, 6".
'Round file, 8".
Wire gauze or asbestos board.
'Wing-top burner.
Mortar and pestle, 4".
Iron spoon.
2 Derlagrating spoon,
i 2 Glass rod, 5".
i Two-hole rubber stopper to
fit large test tubes.
3 ft. rubber tubing, 3/ 16 ".
3 ft. glass tubing, medium wall,
Test tubes,
Test tubes, 6x^".
Test tubes, gx i".
Beaker, 100 c. c.
Beaker, 250 c. c.
Flask, 100 c. c.
Flask, 250 c. c.
Retort, 250 c. c.
Glass plates, 4x4".
Thistle tube.
Funnel, 2^".
'Porcelain crucible, i oz.
'Pipestem triangle.
Evaporating dish, 3".
2 Test-tube holder.
2 Test-tube brush.
Test-tube rack.
to fit rubber stopper.
1 These pieces of apparatus may be used by several students in common.
2 These pieces of apparatus may readily be made by the student himself.
[ xxxvi ]
Laboratory Equipment
xxxvii
LIST B
TABLE APPARATUS
This list includes the apparatus which should be kept at the
laboratory desk used by the student or on a side table. It is a
part of the equipment to be used by different classes.
'Mohr pinch-cocks.
'Iron and copper wire.
'Sand.
'Graduated cylinders, looc. c.
and 500 c. c.
'Bar magnets.
'Splinters of wood.
'Wax tapers.
'Meter sticks.
'Trip scales and weights.
'Chaslyn balances.
i It is not feasible to give quantities for these articles ; as many as
possible should be provided, although it is possible to get along with few.
i Retort stand with two rings
and a clamp.
6 Wide-mouthed bottles or
receivers.
i Pneumatic trough,
i Bunsen burner.
3 ft. rubber hose for attaching
Bunsen burner.
'"Acid bottles."
'Assorted corks.
'Hofmann screw-cocks.
LIST C
DEMONSTRATION APPARATUS
This list comprises the apparatus which the teacher should
have for demonstrating experiments. It should be of the best
quality and not mere makeshift.
i Eudiometer and trough,
i Electrolysis of water appa-
ratus.
i Safety tube.
1 Kipp's gas generator (it is
well to have two or three
all charged and ready to
deliver at any time such
gases as hydrogen, carbon
dioxid, etc.).
2 U-tubes, 6" and 8".
i Liebig's condenser.
Thermometer.
Bulb tube.
Induction coil.
Battery to run coil.
Large lamp chimney.
'Rubber stoppers of various
sizes.
'Ignition tubes.
'Supply of glass tubing of
various sizes.
'Supply of rubber tubing of
various sizes.
i Refer to note in List B.
XXXV111
Elementary Chemistry
LIST D
CHEMICALS
The chemicals should as far as possible be of " c. p." grade.
Acid, acetic.
citric.
hydrochloric.
nitric.
oxalic.
pyrogallic.
sulfuric.
tartaric.
Alcohol, ethyl.
methyl.
Alum, chrome.
potash.
Aluminum, metal.
sulfate.
Ammonium, chlorid.
hydroxid.
nitrate.
oxalate.
sulfid.
Antimony, metal.
Arsenic, metal.
Arsenious oxid.
Asbestos.
Barium, chlorid.
nitrate.
Bismuth, metal.
nitrate.
Bleaching powder.
Borax.
Cadmium chlorid.
Calcium, carbid.
carbonate (marble).
chlorid.
fluorid.
oxid (lime).
sulfate (gypsum).
Carbon bisulfid.
Charcoal, animal.
wood.
Coal, hard.
soft.
Cobalt, chlorid.
nitrate.
Cochineal.
Copper, metal.
nitrate.
sulfate.
Ether.
Glycerin.
Indigo,
lodin.
Iron, metal (filings and wire).
chlorid.
sulfate.
sulfid.
Lead, metal.
nitrate.
monoxid (litharge).
red.
Litmus,
paper.
Magnesium, metal (powdered
and ribbon).
sulfate.
Manganese, dioxid.
sulfate.
Mercury.
Mercuric chlorid.
nitrate.
oxid.
Mercurous nitrate.
Nickel chlorid.
Laboratory Equipment xxxix
Phenolphthalein. Sodium, metal.
Picture cord (iron). bicarbonate.
Potassium, metal. carbonate.
bromid. chlorid.
carbonate. hydroxid.
chlorate. nitrate.
chromate. phosphate.
dichromate. silicate.
ferricyanid. sulfate.
ferrocyanid. sulfite.
hydroxid. Stannous chlorid.
iodid. Starch.
permanganate. Strontium nitrate.
sulfate. Sulfur, flowers and roll.
sulfocyanid. Tin, granulated.
Rosin. Vaseline.
Silver nitrate. Zinc, granulated and sheet.
Soda-lime. sulfate.
W^TT^
-5, '43 (6061 S)
V/D \ / r\ / *
ID IDOO4
50