TP Z45 N8G75 UC-NRLF MINISTRY OF MUNITIONS : MUNITIONS INVENTIONS DEPARTMENT. NITROGEN PRODUCTS COMMITTEE, PHYSICAL AND CHEMICAL DATA OF NITROGEN FIXATION. WITH 47 DIAGRAMS. Specially Compiled for Use in Connection with the SYNTHESIS AND OXIDATION OF AMMONIA AND THE PREPARATION AND PURIFICATION OF HYDROGEN. M.l.D. RESEARCH LABORATORY, UNIVERSITY COLLEGE, DECEMBER, 1918. Price 3s. Net. * INTRODUCTION. THIS publication, containing a summary of physical and chemical data relating to the problems of nitrogen fixation, was first issued by the Munitions Inventions Department in April last and several hundred copies have now been circulated to British and Allied Government Departments and controlled works. Numerous enquiries have since been received from others desirous of obtaining copies and it has therefore been decided to place it on sale to the general public. At the suggestion of the Controller of Munitions Inventions, it may perhaps be useful if I indicate briefly its origin and objects. In the course of the investigations proceeding at the M.I.D. Research Laboratory on certain processes for nitrogen fixation and allied problems, it became necessary to collect from all kinds of sources, some of which were not easily accessible, data relating to the subjects of the researches in question. At the outset, members of the Staff investigating the various branches had dealt with their different problems individually, but it became evident that much time would be saved if a more detailed critical examination of the chemical and physical constants available was undertaken and a compilation made summarising in a handy form the more important of these. I therefore requested Mr. G. W. Todd, D.Sc., B.A., Physicist to the M.I.D. Laboratory, to undertake this task, acting myself as general editor. This first publication has been compiled mainly by him after consultation with Lieut. H. C. Greenwood, D.Sc., Capts. J. R. Partington, D.Sc., and E. K. Rideal, Ph.D., and Dr. H. S. Taylor, the heads of sections of the Laboratory dealing with synthetic ammonia, the oxidation of ammonia, and the preparation and purification of hydrogen, respectively. On some of the subjects dealt with Dr. Todd has not been satisfied with gathering together from the different sources the meagre information available, but has exhibited considerable ingenuity in utilising these to advantage. In the majority of cases reference has been made to the original papers, instead of simply extracting the required figures from the usual books of constants. The graphic form of presentation has been adopted deliberately, since for most purposes amply sufficient accuracy in the value requited can usually be obtained by the use of graphs instead of a table, interpolation thus being altogether avoided. At the same time by means of a graph there is often also presented a general grasp of the facts not at once obvious from columns of figures. Thus the curve of freezing points of nitric acid (Fig. 25) shows that there are three different concentrations of acid having a freezing-point of 30 C., and five strengths freezing at 40 C. Although only few of the data here presented depend on actual determinations carried out at the M.I.D. Laboratory, a considerable number of the tables and curves embody the results of special investigations and computations. Dr. Todd's mathematical treatment of the very important question of the oxidation of nitric oxide to peroxide, given in the Nitric Acid section, should be of distinct service in its application to tower design in the arc process for the fixation of nitrogen and in the ammonia oxidation and Hausser processes. So far as I am aware, his work offers the first general mathematical solution of the problem. Again, the data on the behaviour of oxygen, nitrogen and hydrogen gases under pressure depend on a theoretical investigation of the whole question of the departure from Boyle's law of gases under high pressure, made by Mr. C. Cochrane, M.A., B.Sc. His results, which have been closely confirmed by subsequent experiments, show that, contrary to pre- conceived ideas, the divergence is of an order which is much too large to be neglected in technical practice. As an example of specially computed tables may be instanced the series of curves repre- senting the percentage of ammonia and of nitrogen peroxide theoretically removable from a mixture containing the gas in varying percentages. These have been calculated so as to give, in a convenient form, full details as to the theoretical possibilities of the process of separation of the liquefiable constituent by freezing. This publication in its present form is to be regarded rather as an instalment than as a completed work, and the Munitions Inventions Department would be glad to have their attention drawn to any errors which it may contain, and to receive from users any criticisms or suggestions for its improvement, especially in regard to data the incorporation of which would render it more valuable. One or two minor corrections only have been introduced into this second issue, which is substantially a reprint of the earlier edition. That the errors frequently found in the first edition of a book of this kind were so few is due to the care with which the original manuscript was prepared for the press and the proofs corrected by Mr. William Hill, B. A., of the Headquarters Staff of the Munitions Inventions Department. J. A. BARKER, Director of Research. Munitions Inventions Research Laboratory, University College, London, December, 1918. 3 CONTENTS. GAS DATA. SECTION I. PAGE 1. DEVIATION OF HYDROGEN AND NITROGEN FROM BOYLE'S LAW AT HIGH PRESSURES. AMAGAT'S PV CURVES FOR HYDROGEN AND NITROGEN - - 5 2. HYDROGEN-NITROGEN MIXTURE (N 2 + 3H 2 ) AT HIGH PRESSURES - 6 3. VAN DER WAALS' CONSTANTS AND CRITICAL DATA - - 7 4. DENSITY OF GASES - - - - 8 5. VISCOSITY OF GASES - - - - - - - 8 (a) Air, N 2 , H 2 , NO, Steam, &c. ....... 9 (6) Mixtures of N 2 and H 2 - - 9, 10 (c) N 2 + 3H 2 mixture at different temperatures - - 10 (d) NH 3 and H 2 mixtures at 12 to 13 C. - - 10 6. SPECIFIC HEAT OF GASES - ... - - 11 (a) At constant pressure - - 11 (b) At constant volume - - - - - - - - -12 (c) Specific heat of N 2 + 3H S mixture under pressure - - 13 (d) Specific heat of N 2 + 3H 2 + n per cent. NH 3 mixtures - - 14 (e) Ratio of specific heats - - 14 7. THERMAL CONDUCTIVITY OF GASES - 15 (a) Air, Hydrogen, Nitrogen, Ammonia, Nitric Oxide, &c. - ... 16, 17 (b) Conductivity of Gaseous mixtures - 17 (c) Conductivity of N 2 + 3H 2 mixture - - 17 SECTION II. AMMONIA DATA. 1. AMMONIA EQUILIBRIUM - - 18 Variation with pressure and temperature - ..... 18 2. VAPOUR PRESSURE OF ANHYDROUS AMMONIA - - - - 18 (a) Condensation of NH 3 from a Gaseous Mixture - - 19 (b) Percentage of NH 3 theoretically removable by cooling ... - - 20 3. VAPOUR PRESSURE OF AMMONIA SOLUTIONS - - 20 (a) Total pressures at different temperatures and concentrations - - 20 (6) Partial pressures of NH 3 and H 2 O above solutions ... 20, 21 4. DENSITY OF ANHYDROUS AMMONIA AT DIFFERENT TEMPERATURES - - 21 5. MELTING POINT AND BOILING POINT OF ANHYDROUS AMMONIA - 21 6. DENSITY OF AMMONIA SOLUTIONS AT 15 C. - - 21 7. SOLUBILITY OF AMMONIA AT DIFFERENT TEMPERATURES AND PRESSURES - - 21 8. FREEZING POINTS OF AQUEOUS AMMONIA - 22 9. HEATS OF SOLUTION OF LIQUID AND GASEOUS AMMONIA - 22 10. HEAT OF FORMATION OF AMMONIA FROM ITS ELEMENTS - 22 11. SPECIFIC HEATS OF ANHYDROUS AND AQUEOUS AMMONIA - 2*4 12. LATENT HEATS OF AMMONIA - 2i> SECTION III. NITRIC ACID DATA. 1. SPECIFIC GRAVITY OF AQUEOUS HNO 3 AT 15 C. 24 2. BOILING POINTS OF PURE HNO 3 (99-79 PER CENT.) AT DIFFERENT PRESSURES - 24 3. BOILING POINTS OF AQUEOUS HNO 3 AT DIFFERENT PRESSURES - 24 4. VAPOUR PRESSURE OF AQUEOUS HNO 3 AT DIFFERENT PRESSURES - - 24 5. INFLUENCE OF NON-VOLATILE WATER-RETAINING AGENTS ON THE MAXIMUM BOILING-POINT MIXTURE - 24 6. FREEZING POINTS OF AQUEOUS HNO 3 ... - 24 7. HEAT OF SOLUTION OF NITRIC ACID - - 24 X (33)12343 Wt 17171153 1000 9/20 E & S A 2 593632 SECTION III. cont. PAGE 8. VAPOUK PRESSURES OF OXIDES OP NITROGEN - (a) Condensation of nitrogen-peroxide from a gaseous mixture (b) Percentage of total peroxide theoretically removable by cooling - 25 9. VELOCITY OF THE REACTIONS 2NO + O 2 -* NO 2 AND 2NO + O 2 -* N 2 4 AT CONSTANT PRESSURE AND CONSTANT VOLUME - 25 To find the Velocity Constant To find the time required for Oxidation 10. EQUILIBRIA HYDROGEN PURIFICATION DATA. SECTION IV. 1. WATER-GAS EQUILIBRIUM - 32 2. CARBON CARBON DIOXIDE EQUILIBRIUM 3. CARBON MONOXIDE OXYGEN EQUILIBRIUM - 33 4. DISSOCIATION OF WATER VAPOUR - 34 5. EQUILIBRIA BETWEEN THE OXIDES OF IRON AND CARBON - 34 6. IRON OXIDE HYDROGEN EQUILIBRIUM - - 35 7. METHANE HYDROGEN EQUILIBRIUM - - 35 8. DISSOCIATION OF SULPHURETTED HYDROGEN - - 36 9. DISSOCIATION OF CARBON BISULPHIDE - 36 SECTION V. MISCELLANEOUS DATA. 1. HYDROMETER READINGS - - 37 2. SPECIFIC GRAVITY OF SOLUTIONS AT ORDINARY TEMPERATURES - 37 3. SPECIFIC GRAVITY OF AND PERCENTAGE OF SALT IN SATURATED SOLUTIONS - 37 4. SOLUBILITIES AT DIFFERENT TEMPERATURES - 37 '5. VAPOUR TENSION OF WATER AT DIFFERENT TEMPERATURES - - 37 6. VAPOUR TENSION OF NaNO 3 AND KN0 3 SOLUTIONS FOR VARYING CONCENTRATIONS AND TEMPERATURES - - - 37 7. FREEZING POINTS OF: (2) NH^NO^a^H^O 3 } Solutions for Various Concentrations 37 (3) Mixtures of NOj and NO - 38 8. HEATS OF FORMATION - 38 9. HEATS OF MODIFICATION-CHANGE - 38 10. LATENT HEATS OF FUSION - 39 11. LATENT HEATS OF VAPORISATION - 39 MISCELLANEOUS CONVERSION TABLES -40-43 GRAPHS -j Wowing 44 INDEX 45 Further general information on Chemical and Physical Constants may be obtained from : Physical and Chemical Constants. Kaye and Laby (Longmans). 1916, 2nd ed., pp. 153. Referred to in the text as " Kaye and Laby." Smithsonian Physical Tables. Fowle (Smithsonian Institution). 1916, 6th ed., pp. 343. Recueil de Constantes Physiques. Abraham and Sacerdote (Gautier-Villars). 1913, pp. 753. Tables Annuelles Internationales de Constantes. 1912 et seq. (Gautier-Villars). Physikalisch-CJiemische Tabellen. Landolt-Bornstein-Roth. 1912, 4th ed., pp. 1313. Referred to in the text as " Landolt." Physico- Chemical Tables. Castell-Evans (Griffin). 2 vols., pp. 1235. Also from : Ready Reference Tables. Hering (Chapman and Hall). 1914, pp. 196. Technical Chemist's Handbook. Lunge (Gurney and Jackson). 1916, pp. 264. Chemist's Tear-Boole. Atack (Sherratt and Hughes). 1917, 2 vols. pp. 990. SECTION I. GAS DATA. 1. Deviation of Hydrogen and Nitrogen from Boyle's Law at High Pressures. A " perfect " gas obeys Boyle's law PV = RT, where P = pressure, V = volume, and T = absolute .temperature. When T is constant, PV should be constant. Real gases follow this law closely up to pressures of the order of 50 atmospheres, but depart from it considerably at high pressures (see Amagat's curves, Fig. 1). According to Boyle's law, the pressure is proportional to the density, provided the temperature is constant. Natterer (Pogg. Ann., LXII., p. 139 ; XCIV., p. 436) put equal increments of gas into a constant volume and measured the resulting pressures. His values for hydrogen and for nitrogen are given below : HYDROGEN. No. OF MASSES INTRODUCED. ] 8 28 68 128 138 238 248 418 498 608 758 908 1,008 PRESSURE IN ATMOS. 1 8 28 68 134 146 274 287 539 685 958 1,434 2,044 2,790 NITROGEN. No. OF MASSES INTRODUCED. 1 15 75 225 235 355 415 495 605 705 PRESSURE IN ATMOS. 1 15 75 240 252 444 600 882 1,640 2,790 Evidently P is not proportional to the density even in the cases of the nearly " perfect " gases hydrogen and nitrogen. In high-pressure gas work this divergence from Boyle's law must be taken into account. The most reliable data for hydrogen and nitrogen are those of Amagat, given graphically in Fig. 1, where the product PV is plotted. against P, the temperatures being given on the curves. Since no gas obeys Boyle's law exactly, a cylinder of gas at n atmospheres will not yield exactly n times its volume of gas at atmospheric pressure. If gas cylinders of equal volume contain respectively hydrogen, nitrogen, and carbon dioxide at 16 C. and at a pressure of 120 atmospheres, they will yield at the same temperature and at atmospheric pressure 111 '3 times their volume of hydrogen, 120 times their volume of nitrogen and 485 times their volume of carbon dioxide. The following table, which Mr. C. Cochrane has deduced from the PV curves of Amagat and other observers, gives the relative volumes occupied by various gases when the pressure is reduced from the value given at the head of the column to 1 atmosphere : GAS Relative volume which the Gas will occupy when the Pressure (Temp. = 16 C.) is reduced to Atmospheric from 1 atm. 50 atm. 100 atm. 120 atm. 150 atm. 200 atm. " Perfect " gas - 1 50 100 120 150 200 Hydrogen 1 48-5 93-6 111-3 136-3 176-4 Nitrogen 1 50-5 100-6 120-0 147-6 190-8 Air 1 50-9 101-8 121-9 150-3 194-8 Oxygen 1 105-2 212-6 Oxygen (at C.) 1 52-3 107-9 128-6 161-9 218-8 Carbon dioxide - 1 69-0 477* 485* 498* 515* Carbon dioxide is liquid at pressures greater than 90 atmospheres. 6 This table shows that the departures from Boyle's law, even for a gas such as hydrogen, are of considerable technical importance. Thus a purchaser buying hydrogen according to an accurate pressure gauge would be receiving, if the cylinder had its nominal capacity at 120 atmospheres (the usual working pressure), only 92*7 per cent, of his proper amount, and if the pressure were higher a still smaller proportion. For oxygen, on the contrary, the error is in the reverse direction, the table showing that the purchaser would receive over 5 per cent, too much at 100 atmospheres. These considerations are of importance in estimating, for example, the number of cylinders of compressed hydrogen required to fill a balloon or airship of given volume. 2. Hydrogen-Nitrogen Mixture (N 3 + 3H 2 ) at High Pressures. In connection with the synthesis of ammonia, it is often necessary to fill cylinders with the component gases in the right proportions at 100 to 200 atmospheres pressure. One accurate method of doing this would be to mix the gases in the correct proportions at atmospheric pressure before compression, but it is often much more convenient to compress first one gas into the cylinder and then add the other. If the final pressure of a (N 2 +3H 2 ) mixture is to be, say, 200 atmospheres, it will not be correct, even for technical purposes, to add nitrogen at 50 atmospheres and fill up with hydrogen to 200 atmospheres, on account of the deviations from Boyle's law. Mr. C. Cochrane, assuming Leduc's law that " the volume occupied by a mixture of gases is equal to the sum of the 'volumes which the component gases would separately occupy at the same temperature and under the same pressure as the mixture," has deduced the following table for use when the gases are pumped separately into the cylinders : GAS MIXTUKES FOE, THE SYNTHESIS OF AMMONIA. Temperature = 16 C. IF FINAL PRESSURE OF MIXTURE IS TO BE THEN INITIAL PRESSURE OF HYDROGEN SHOULD BE OR INITIAL PRESSURE OF NITROGEN SHOULD BE atm. (abs.) 25 atm. (abs.) 19-0 atm. (abs.) 6-0 50 38-0 12-2 75 56-0 18-0 100 75-0 23-6 125 94-0 29-3 150 111-0 34-4 175 130-0 39-5 200 148-0 44-5 Thus, if it is desired to fill a cylinder to a final pressure of 200 atmospheres and the hydrogen is put in first, the pressure of hydrogen should be adjusted to 148 atmospheres, the nitrogen being afterwards added up to a gauge reading of 200 atmospheres. But if the nitrogen is filled in first, only 44'5 atmospheres are required, instead of 50, which would be the case if Boyle's law were obeyed, the ratio of the partial pressure of the nitrogen to that of the hydrogen being actually 1 to 3 '49, instead of the theoretical 1 to 3. The figures in the table have been calculated from Amagat's PV curves, and it has been found that cj linders pumped up with the gases according to them contain the correct (N 2 + 3H 2 ) mixture for the synthesis of ammonia. 3. Van der Waals' Constants and Critical Data. Several " real " gas equations have been proposed, the best known being that of Van der Waala : where a, 6 are constants characteristic of the gas. The following table has been taken from Physical and Chemical Constants (Kaye and Laby), p. 34 : GAS. CRITICAL TEMPERATURE. CRITICAL PRESSURE. CRITICAL VOLUME. C. Atmospheres. cc. a b Ho -234-5 20 0-00264 0-00042 0-00088 N; - - - -146 33 00517 00257 00156 NH 3 - + 130 115 00481 00798 00161 NO - 93-5 71-2 00347 00257 00116 NO 2 - + 171-2 147 00413 00756 00138 N 2 d - + 38-8 77-5 00436 00710 00184 Air -140 39 00468 00257 00156 2 - - - -118 50 00426 00273 00142 A- - - - -117-4 52-9 00404 00259 00135 CH 4 - 95-5 50 00488 00357 00162 CO -141-1 35-9 00505 00275 00168 CO, - - - + 31-1 73 0066 00717 00191 The critical temperature is the highest temperature at which a gas can be liquefied by com- pressing it. The critical pressure is the pressure which produces liquefaction at the critical temperature. The critical volume is given in the above table as the ratio of the volume that the gas occupies at the critical temperature and pressure to the volume it would occupy at C. and 760 mm. Taking pressures in atmospheres and the volume at C. and 1 atmosphere as 1, then PF J^ T = 273 In these units 6 is in terms of the volume of the gas at C. and 1 atmosphere. BT. a = 64P and b = SP Van der Waals' equation affords an explanation of the form of Amagat's curves. The equation may be written _ where _ PV+\(l-*)=RT. /. PF = ' / 1 bt bRT bRT Hence there is a minimum value of PF for a density given by -7, r~^> = a . (1 o/o) 2 If this equation gives a positive value for p the curves are like those of N 2 . If p is negative the PF curves are like those of H 2 (Fig. 1). As T diminishes, p for the minimum PF increases. This can be seen in the N 2 curves. At much lower temperatures, PF for H g should also show an initial diminution with increasing P or p. 4. Density of Gases. The following table, from the figures given in " Kaye & Laby " (p. 26), gives the density of various gases at C. and 760 ram. pressure : DENSITY OF GASES. r< A o DENSITY DENSITY RELATIVE DENSITY RELATIVE LrAS. (gms. per litre). TO OXYGEN. TO HYDROGEN. Air 1-2928 0-9047 14-385 Oxygen - - 1-4290 1-0000 15-900 Hydrogen 0-08987 0-06289 1-000 Nitrogen 1-2507 0-8752 13-916 Argon - 1-7809 1-2463 19-816 Nitrous oxide 1-9777 1-3840 22-006 Nitric oxide - 1-3402 0-9379 14-912 Ammonia 0-7708 0-5394 8-577 Carbon monoxide - 1-2504 0-8750 13-913 Carbon dioxide 1-9768 1-3833 21-996 DENSITY OP NITROGEN PEROXIDE. The density (oxygen = 16) of nitrogen peroxide at different temperatures and 760 mm. pressure (" Kaye & Laby," p. 26) is given below : > Temp. C. - - - 26 -7 39 -8 60 -2 80 -6 100 -1 121-5 154 -0 183 -2 Density 38-37 35-62 30-12 26-06 24-33 23-46 22-88 22-73 These figures indicate that, while at the lower ranges the gas is almost completely N 2 4 , at the higher temperatures above, say 140 C., it is practically completely dissociated. 5. Viscosity of Gases. The viscosity of. a fluid is measured by the tangential force on unit area of either of two parallel planes at unit distance apart, one of which is fixed while the other moves with the unit of velocity, the space between being filled with the fluid. Or, we may say that the viscosity coefficient 77 is the ratio of the tangential stress T to the velocity gradient dx dv dx T is measured in dynes per sq. cm. ; v is measured in cm. per sec. ; x is measured in cm. The viscosity of a gas changes considerably with temperature, but is practically independent of pressure. (a) VISCOSITY OF GASES. GAS. TEMPERATUEE C. VISCOSITY (17,). Air -21 0-000164 0171 Hydrogen - -21 15 99 302 0-0000819 0841 0889 0-000106 139 Nitrogen -21 11 54 183 0-000157 366 171 190 246 Oxygen - 15 54 0-000187 195 216 Nitric Oxide - 20 0-000165 186 Water Vapour - - 15 \ 100 0-000090 097 132 Sutherland gives for the variation with temperature : 273 + C j \f where = absolute temperature and C = constant. (&) VISCOSITY OF N 2 AND H 2 MIXTURES. Reference : Kleint, Ver. phys, Ges., 7, 146, 1905. PER CENT. Ho. PER CENT. N 2 . TEMPERATURE C. r) t X 107 >?o X 107 SUTHERLAND'S C. 0-0 100-0 14-6 99-8 182-7 1742 2125 2459 1671 118 19-97 80-03 15-7 99-6 183-1 1714 2077 2405 1639 114 36-20 63-80 14-2 99-7 183-4 1659 2011 2321 1595 104 [ Table continued over x 12343 10 (6) VISCOSITY OF N 2 AND H 2 MIXTURES (continued}. PER CENT. H 2 . PEE CENT. N s . TEMPEEATUEE C. rj t X 107 T?O X 107 SUTHEELAND'S 0. 53-55 46-45 14-6 99-8 183-4 1583 1921 2216 1522 104 82-61 17-39 17-0 99-9 183-2 1328 1593 1829 1269 94 93-62 6-38 16-7 99-9 183-7 1116 1329 1529 1067 86 100-0 o-o 18-O- 100-4 183-8 873 1050 1212 841 91 From Kleint's results we can deduce the viscosity of N 2 + 3H 2 mixture at different temperatures. The following table is deduced from Kleint's figures : (c) VISCOSITY OF N 2 + 3H 2 MIXTURE AT VARIOUS TEMPERATURES. TEMP. C. - 17 100 183 77 X 107 1350 1450 1710 1970 Putting these figures into Sutherland's formula gives C = 96, whence x 107 = 2760 T 6 oo x 1Q7 = 2950. (d~)~ VISCOSITY OF NH 3 AND H 2 MIXTURES AT 12 TO 13 C. Reference : Thomsen, Ann, d. Phys., 36, pp. 825, 832. VOL. OP H 2 IN 100 VOLS. MIXTUEE o-o 8-2 20-1 33-9 53-6 68-4 79-1 90-2 100-0 ?) X 107" - 1005 1017 1042 1068 1102 1104 1089 1036 915 NOTE ON THE FLOW OF GASES THROUGH PIPES. When the velocity of flow of a gas is below a critical value, depending on the density and viscosity and on the diameter of the tube, the gas moves in stream-lines parallel to the axis of the tube Above this critical velocity the stream-lines disappear and the flow becomes turbulent. 77 The critical velocity V c = Jc for small pipes up to, say, 5 cm, diam., where k is a constant, p is the gas density and r is the tube radius. When V c , 77, p and r are in C.G.S. units, fcis 10 3 in round numbers. 11 Below the critical velocity the pressure drop along a tube is proportional to the velocity of gas flow. Above the critical velocity the pressure drop is practically proportional to the square of the velocity. 6. Specific Heat of Gases. The specific heat of a substance is the quantity of heat in gm. calories required to raise 1 gram of it through 1 C. The specific heat of a gas at constant pressure C is always greater than the specific heat at constant volume C v , Thermodynamics gives r\ n m (&P \ fdv \ C P ~ > =-~ J- (jm) (jm) \oa / \aj./ p Whence fora gas which follows Boyle's law, C C v = R and for a gas which follows Van der R in gm. cals. per gm. mol. = I 1 985. Waals'law, C, - C v = R j 1 + 2a (a) SPECIFIC HEATS AT CONSTANT PEBSSURE. AIR. The following Table for Air (C p and its variation with temperature) is taken from Landolt, p. 773 : TEMP. C. - - 183 -30 to +10 to 100 20 to 440 20 to 630 20 to 880 c, - - - 0-253 0-238 0-237 0-237 0-243 0-243 Witkowski gives variation with temperature and pressure as follows 1 atmosphere - 102 to + 98 C. 0-237 40 atmospheres - ' - 40 40 - - - - - 140 -120 - 50 2-607 0-470 0-274 70 - - - - 70 - - - - - 120 - 50 0-777 0-312 The following table, showing the variation with pressure of G for air at 60 C., is given by Holborn and Jakob (Z. Ver. deut. Ing., 58, 1429, 1914). Three observers are in fair agreement. PRESSURE. HOLBORN AND JAKOB'S VALUES. LUSSANA'S VALUES. VOGEL'S VALUES. NOELL'S VALUES. (Atmospheres). 1 0-2415 0-2370 25 2490 2711 0-2480 0-2490 50 2554 3061 2543 2568 100 . -2690 3675 2664 2701 150 2821 4195 2770 2812 200 2925 2853 2893 B 2 12 6. Specific Heat of Gases (continued). Recent experiments of Holborn and Jakob (Z. Ver. deut. Ing., 61, p. 146, 1917) give for air at 60 C. between pressures of 1 and 300 atmospheres : 10 4 C = 2414 + 2 86p + 0005p 2 - 0000106p 3 . HYDROGEN. Regnault - - - 28 to + 9 C. - - 3 -400 Wiedemann- - + 21 to + 100 - -3-410 Regnault - + 12 to + 198 - - 3 -409 Lussana gives variation with pressure : 1 atmosphere, 3 '402 ; 30 atmospheres, 3 '788. NITROGEN. Scheele and Heuse - - at 20 C. - 0'249 Regnault - - - to 200 - - 0'244 Alt gives for liquid nitrogen - 208 to - 196 - 0'430 AMMONIA. Wiedemann - - 23 to 100 C. - - - - 0*520 27 to 200 ... - 0-536 Nernst - 365 to 680 - - 0'65 Tamaru (Z. Electroch., 21, p. 240, 1915) gives for ammonia C p =8-62 + 0-0035* + 5-1 X 10-6*2, where C p is the heat in gm. cals. required to raise 1 gm. mol. through 1 C. at a temperature t C. NITROUS OXIDE : Wiedemann - 26 to 103 C. - 0-213 NITRIC OXIDE: Regnault- 13 to 172 C. - 0-232 NITRIC PEROXIDE : Berthelot and Ogier - 27 to 67 C. - 1-625 WATER VAPOUR: Holborn and Henning - - at 100 C. - - 0-465 (&) SPECIFIC HEATS AT CONSTANT VOLUME. AIR. Holborn f" and < Henning I - at 100 C. 600 C. 1100 C. 0-163 - .-. - - 0-173 0-191 HYDROGEN. Joly Pier - at 50 C. - to 2500 C. - - - 2-40 2-89 NITROGEN. Pier ..... to 2500 C. - - - 0-215 Mallard and Le Chatelier give for N 2 up to 3000 C. C 9 =0-1 70 + 0-0000872*. AMMONIA Voller - at 18 C. - 0'390 WATER VAPOUR. Pier ..... at 100 C. - - - 0-340 13 (c) SPECIFIC HEAT AT CONSTANT PRESSURE OF N 2 + 3H 2 MIXTURE UNDER VARIOUS PRESSURES. Assuming, as is justifiable, that the heat capacity of the mixture is the sum of the heat capacities of the constituents, we obtain CP= 0'806 between and 100 C. and at 1 atm. pressure. Holborn and Jakob's figures show that for air at 60 C. a linear law holds, namely : where P = absolute pressure in atmospheres, a = 0'0013, and Ci = specific heat at 1 atmosphere. Assuming the linear law and taking Witkowski's values at low temperatures, we get for air at - 50 C. a = 0-0056; at - 120 C. a = O'Oll. These scanty data suggest that aT 2 (where T is the absolute temperature) is constant, so that da constant dT = ~T When T is great, the change of a with T will be small and negative. The only other datum on change of specific heat with pressure is that of Lussana, given above for hydrogen. Assuming the linear law, then, for hydrogen at ordinary temperatures a = 0'0037.* If we take a for nitrogen to be the same as a for air, i.e., 0'0013, we shall not make a grave error in putting a for N 2 + 3H 2 mixture equal to 0'0025 at ordinary temperatures. Hence we may take the specific heat at constant pressure of N 3 + 3H 2 mixture as given by : Cp = cJl +0-0025 (P-l)} ; or, C P = 0'80 + 0-002 (P- 1). At high temperatures the coefficient of (P 1) may be slightly less. The following values are deduced from this expression* : P atmospheres ------ 1 30 50 100 150 200 Specific heat at cons, press. 0-80 0-85 0-90 1-00 1-10 1-20 dp\ p ) = ~ T {dT 9 ) Thermodynamics gives whence* C p C } Modifying Van der Waals' equation to Whence C p - C, = ^(P-l), or, C p = C, { 1 + J^ (P - 1) } . This gives da constant dT = ~T^~ Modifications of the other gas equations also give approximately linear relations between C and pressure. * Experiments made in the M.I.D. laboratory on hydrogen suggest a much lower value for a, so that the figures in the table may be too high. Gr.W.T. 6. Specific Heat of Gases (continued). (d) SPECIFIC HEAT OF N 2 + 3H 2 + n PER CENT. NH 3 MIXTURES. Assuming that the heat capacity of the mixture is the sum of the heat capacities of the constituents, the following table has been calculated for 1 atmosphere pressure at ordinary temperatures : Per cent. NH 3 (by vol.) 0-806 1 0-802 2 3 . 4 5 Specific heat 0-797 0-790 0-782 0-779 Taking the pressure coefficient as 0'025, 'approximate values of the specific heat at higher pressures can be obtained. At temperatures of 365 C. to 680 C. Nernst gives C p for ammonia as 0'65. This, however, does not affect the figures in the above table, the percentages of ammonia being so small. (e) RATIO OF THE SPECIFIC HEATS (y). The ratio of the specific heats of air, nitrogen and hydrogen is for all practical purposes independent of the temperature. AIR. y at different temperatures (various observers). Reference : Landolt, p. 775. TEMP. C. - -181 -156 18 100 900 950 y- 1-34 1-39 1-405 1-405 1-403 1-39 1-34 OBSERVER - Cook Wullner Rontgen Leduc Kalahne Stevens Partington (Phys. Zeit, 1913) gives at 18 C., y = 1 '403. Holborn and Henning obtain from explosion experiments (Ann. d. Phys., 23, 1907) : TEMP. C. - 100 600 1100 y 1-404 1-38 1-345 The ratio y may change considerably with pressure, as the following (Koch) shows : table for air at 79 C. PRESS, (atm.) - 1 25 50 100 150 200 y . - 1-405 1-569 1-767 2-200 2-469 2-333 15 Apparently y has a maximum value in the neighbourhood of 150 atmos., where its value is 75 per cent, greater than its value at 1 atmosphere. It is impossible to say whether this same increase would take place if the temperature were 500 or 600 C., instead of 79 C. HYDROGEN. y = 1 -41 - - Cazin. - Maneuvrier and Fournier. = 1 '408 (4 to 16 C.) - - Lummer and Pringsheim. No data are available for different pressures. NITROGEN. y = 1-45 (at -192 C.) .. ., Valentiner. = 1.41 - - - Cazin. = 1-389 - - Rohlf. No data are available for different pressures. AMMONIA. y = I -262 (21 to 40 C.) - - - - - - Miiller. -1-317(0) - .... Wifflner. = 1-277(100) - No data are available for different pressures. HYDROGEN-NITROGEN MIXTURES. For any mixtures of N 2 and H 2 at ordinary temperatures and pressures, y ] 40. The same value may be taken when a small percentage of NH 3 is present. At high pressures the value of y may be considerably changed. (See AlR.) NITRIC OXIDE : y = 1 394 ... Masson. NITRIC TETROXIDE (N 2 4 ) : y = 1-172 (20 C.) (15 per cent, dissociated; press. = 641 mm.). Natanson. = 1-274 (22 C.) (60 ; press. = 44 mm.). Natanson. NITRIC PEROXIDE : y = l-31 (150 C.) Natanson. WATER VAPOUR : y = 1 305 (100 C.) Makower. 7. Thermal Conductivity of Gases. If two opposite faces of a cm. cube of substance are maintained at temperatures differing by 1 C., then the heat in gm. cals. which passes through the cube in 1 second is the thermal conductivity of the material. The kinetic theory of gases leads to the expression for thermal conductivity k = AyC v) where A = I'Q for diatomic gases or 2 6 for monatomic gases ; f) = viscosity coefficient ; C v = specific heat at constant volume. Pollock (Phil. Mag., 31, p. 52) gives A as a function of y. _ 1 = 7-32(y-l). 7" According to the kinetic theory the viscosity coefficient ^ should be independent of pressure, and for a wide range of pressures experiment agrees with theory. It follows that k should be independent of pressure provided C v is also independent of pressure. We have seen that both C and y may have 16 7. Thermal Conductivity ol Gases (continued). pressure coefficients and, if these pressure coefficients are unequal, C t will not be independent of pressure. The thermal conductivity of a gas may, therefore, have a different value at pressures of 200 atmospheres. In this connection it is interesting to see what the application of thermodynamics suggests, W e have A gas which follows Van der Waals' law gives = > whence C, is independent of the volume of gas and therefore independent of the pressure. Other gas equations (such as that of Clausius) give, however, so that C v is not independent of the pressure. Investigation shows that C v may be taken approximately as a linear function of the pressure, the coefficient not necessarily being the same as the pressure coefficient of C p . (a) THERMAL CONDUCTIVITY OF GASES. Nearly all experiments on thermal conductivity of gases have been carried out at pressures of a few cm. of mercury to avoid convection difficulties. GAS. TEMPERATURE C. & TEMPERATURE COEFFICIENT. OBSERVER. AIR at low pressures (1-3 cm.) i) > 0-0000492 568 483 562 557 467 479 0-00203 183 281 360 Kundt and Warburg. Winkelmann. Graetz. Schleiermacher. Mtiller. Eckerlein. Compan (Landolt, p. 742). at 1 atm 55 osphere 0-0000571 Todd (Proc. Roy. 8oc., A. 83, 1909). HYDROGEN at low pressures (1-3 cm.) 0-000327 319 410 318 387 0-00206 22 275 42 Winkelmann. Graetz. Schleiermacher. Eckerlein. Giinther (Landolt, p. 742). NITROGEN at low pressures (1 - 3 cm.) 8 0-0000569 524 Gunther. Winkelmann (Landolt, p. 742). at 1 atm 55 osphere 0-0000569 Todd (Proc. Roy. Soc., A. 83, 1909). AMMONIA at low pressure 100 0-0000458 709 0-00513 Winkelmann (Landolt, p. 742). \_Table continued on p. 17. 17 (a) THERMAL CONDUCTIVITY OF GASES (continued). GAS. TEMPERATURE C. k TEMPERATURE COEFFICIENT. OBSERVER. NITROUS OXIDE at low pressure 100 0-0000350 506 Winkelmann. NITRIC OXIDE 8 0-0000460 Winkelmann. at 1 atmos 55 phere 0-0000539 Todd. NITRIC PEROXIDE at 1 atmos 55 phere 0-0000888 Todd. (6) CONDUCTIVITY OF GASEOUS MIXTURES. When the constituents of the mixture have nearly the same viscosities and not very different specific heats, the thermal conductivity may be obtained from the viscosity of the mixture by applying the formula : k = Af) C = Arj^ y This equation, however, gives incorrect values when the viscosities of the constituents are not of the same magnitude. Thus, for air, the above formula gives a value for the thermal conductivity in fair agreement with experimental determinations. For (N 2 -j- 3H 2 ) mixture the formula gives a value which is probably much too low. It can be shown theoretically that the thermal conductivity of a mixture of two gases is given by 1 + A 1 + Pi where ki and k z are the conductivities of the constituents, )) Pi Pa partial pressures of the constituents, P-2 and A = % where 17! and >? 2 are viscosities, mi and m 2 are masses of molecules and B = A. (c) CONDUCTIVITY OF (N 2 + 3H 2 ) MIXTURE. Let us take the following data for the constituent gases : O o r I Hydrogen ^ = 0-00035 ^ = 0-0000841. ' I Nitrogen fe a = 0-000052 ^ = 0-000166. 10Q o r I Hydrogen ^ = 0' 00044 ^ = 0-000106. ' I Nitrogen k z = 0-000068 ^ 2 = 0-00021. At each temperature, 2 1/1 ^1 _ n-^l 2>i Q = 14 , = u 01 , = d . Whence A } '14, and B.= 2'2A, giving 'bo = 0-00026 and k m = 0-00033, x 12343 18 SECTION IL AMMONIA DATA. 1. Ammonia Equilibrium. PERCENTAGE OF AMMONIA IN EQUILIBRIUM WITH THE MIXED GASES (N 2 + 3H 2 ). Haber gives the following table for the equilibrium at various temperatures and pressures (Z. Electroch., 20, 600, 1914). The figures have been plotted in Figs. 2 and 3 : PER CENT. NH 3 IN EQUILIBRIUM AT PRESSURES (IN ATMOSPHERES) OF 1 30 100 200 200 15-3 67-6 80-6 85-8 300 2-18 31-8 52-1 62-8 400 0-44 10-7 25-1 36-3 500 129 3-62 10-4 17-6 600 049 1-43 4-47 8-25 700 0223 0-66 2-14 4-11 800 0117 35 1-15 2-24 900 0069 21 0-68 1-34 1,000 0044 13 44 0-87 Haber gives the following formula for the equilibrium constant at a pressure of 1 atmosphere, which agrees well with experimental determinations between the temperatures 500 C. and 1000 C. 13200 Iog 10 K = ~T7K. x If the percentage of NH 3 is small and the total pressure is 1 atmosphere, we may take p NUz = ()* X (f) s X K p = 0-325 K p } p NHz being in atmospheres. Hence, if E is the equilibrium percentage of NH 3 , we have at 1 atmosphere between 500 C and 1000 C. which agrees well with the figures foi 1 atmosphere given in the table. 2. Vapour Pressure of Anhydrous Ammonia. The results obtained by various experimenters (see Landolt's tables, p. 379) on the vapour pressure of anhydrous ammonia are given in the following table. The results have been plotted in the graphs 19 in Fig. 4, which also give, of course, the boiling points of anhydrous ammonia at different pressures. The data deduced therefrom concerning the condensation of ammonia from gaseous mixtures are given in paragraphs (a) and (6). VAPOUR PRESSURE OF ANHYDROUS AMMONIA. R Begnault P Pictet Mem. de VAcad., 26, 535. Arch, de Geneve, 13, 212. B Brill - - Ann. Phys. (4), 21, 170. D Davies - Proc. Roy. Soc., A., 78, 42. TEMPERATURE C. PRESSURE OF SATURATED VAPOUR. - 80 (Solid) 35-2 mm. (B) -77-6 (M.pt.) 44-1 -70 77-2 -60 166-6 -50 323 -3 mm. (B) 293 mm. (D) -40 563 1 557 , -30 867mm. (D) l-14atm. (P) 1-14 atm. (R) -25 1098 1-45 1-45 -20 1393 1-83 1-83 -15 1726 2-28 2-24 -10 2146 2-82 2-82 - 5 2617 3-45 3-45 4-19 4-19 ., + 5 5-00 5-04 10 6-02 6-02 15 V-12 7-14 ,, 20 8-40 8-41 25 9-80 9-84 30 11-44 11-45 35 13-08 13-25 40 15-29 15-26 45 17-38 17-48 50 19-98 19-95 55 22-66atm .(R) 60 25-63 65 28-90 70 32-47 75 36-35 80 40-59 85 45-17 90 50-14 95 55-52 100 61-32 " (a) CONDENSATION OF AMMONIA FROM A GASEOUS MIXTURE. In Figs. 5 and 6 graphs have been constructed from Fig. 4 showing at what temperatures and total pressures, condensation should begin for various percentages (by volume) o ammonia in a gaseous mixture. These graphs give the maximum percentages of ammonia that can exist in a gaseous mixture under various temperatures and pressures. Thus at 10 C and 140 atmospheres the ammonia content cannot be greater than 2 per cent. (Fig. 5). The graphs were obtained by reasoning as follows. Let the vapour pressure of anhydrous ammonia at t C. be p . In other words, the boiling point of liquid ammonia under a pressure p t is t C. C 2 20 2. Vapour Pressure of Anhydrous Ammonia (continued'). If a not easily liquefiable gas contains 50 per cent. NH 3 at a temperature of t a C., obviously the total pressure must be 2p t before liquefaction of the NH 3 sets in. Generally, if x per cent. NH 3 is present at t C., the pressure required for liquefaction to begin will be PI' (b) PERCENTAGE OF AMMONIA THEORETICALLY REMOVABLE BY COOLING. Further graphs (Figs. 7, 8 and 9) have been constructed from Figs. 5 and 6 showing the percentage of ammonia which, theoretically, can be removed from gaseous mixtures by cooling under pressures of 50, 100, 150 and 200 atmospheres. These have been obtained in the following way. Let the NH 3 content be x per cent. By increasing the pressure on the gas or by lowering the temperature we can reach a point (shown by Figs. 5 and 6) at which condensation will begin in a mixture containing, say, y per cent. NH 3 ; that is to say, x y per cent, will have been liquefied, i.e., a fraction - - of the original content of ammonia. 3. Vapour Pressure of Ammonia Solutions. (a) TOTAL PRESSURE (AMMONIA + WATER VAPOUR) AT DIFFERENT TEMPERATURES AND CONCENTRATIONS. The following table (Hilde Mollier, Fors. d. ver. deutsch. Ing., Berlin, 1909) gives the total pressures in mm. In Fig. 10 the results-are graphed in convenient form, the pressures being given in atmospheres : PRESSUBE IN MM. OF MEBCUBY. Per cent. NH 3 20 30 40 50 60 70 80 90 100 110 120 130 140 150 5 972 1342 1831 2447 3235 4200 5350 30 770 1091 1520 2060 2745 3620 4672 5890 7500 15 823 1166 1616 2200 2937 3850 4980 6350 20 840 1200 1670 2270 3055 4030 5210 6708 25 837 1208 1680 2308 3120 4145 5400 i 6950 30 820 1197 1676 2320 3155 4200 5510 7070 35 793 1157 1652 2305 3142 4238 5570 7155 40 1103 1594 2260 3120 4190 5550 7135 45 1487 2138 3000 4080 5410 7030 50 1960 2790 3850 5210 6810 (b) PARTIAL PRESSURES OF AMMONIA AND WATER VAPOUR ABOVE SOLUTIONS. Perman (J. Chem. Soc., 83, 2, 1169, 1903) has measured the partial pressures at different temperatures for various concentrations of ammonia. Some of his figures are given in the Table below. These have been plotted in Fig. 11 and the graphs in Figs. 12 and 13 have been constructed from Fig. 11 to give at a glance the value of the partial pressure at any temperature. Figures 12 and 13 have been deduced from Perman's figures and must be considered as approximate only. It is interesting to note that according to Perman'e figures the partial pressure of water vapour above a 5 or 6 per cent, solution at C. is greater than the vapour tension of pure water at that temperature. PARTIAL PRESSURE OF NIL AND OF H 2 ABOVE SOLUTIONS. t C. PER CENT. NH 3 PARTIAL PRESSURE MM. t C. PER CENT, NH 3 PARTIAL PRESSURE MM. NH 3 H 2 NH 3 H 2 4-72 9-15 14-73 19-62 22-90 11-4 24-8 51-3 82-5 116-6 5-1 5-3 4-1 3-0 2-8 30-09 3-93 7-43 12-77 17-84 21-47 41-2 86-3 175-0 291-1 404-6 31-1 29-2 26-6 24-3 22-1 40 3-79 11-06 15-55 20-85 61-1 218-5 353-6 576-1 53-5 49-1 44-1 37-8 10 4-16 8-26 12-32 15-88 20-54 21-83 16-5 37-2 64-2 95-1 149-2 169-8 9-1 8-8 7-6 7-0 7-2 5-5 50 3-29 8-91 14-15 14-94 79-1 246-6 451-4 487-1 89-6 83-0 77-0 75-2 19-9 4-18 6-55 10-15 16-64 23-37 27-4 46-0 80-6 166-1 302-4 16-4 16-0 15-1 12-9 10-3 60 3-86 7-78 11-31 136-9 300-4 475-8 144-1 138-5 130-4 4. Density of Anhydrous Ammonia at different Temperatures. Fig. 14 has been plotted from the results of Lange (Z. Ges. Kalte-Ind., 5, 39, 1898) and Dieterici (Z. Ges. Kalte-Ind., 11, 2.1 and 47, 1904). Tables are not given, bnt the experimental determinations are shown in the graphs, and the density of saturated vapour is also given. 5. Melting Point and Boiling Point of Anhydrous Ammonia. MELTING POINT : BOILING POINT : - 75 C. Faraday - - 1845 -75-5C. Ladenburg - - 1900 -77-7C. Brill - - - 1906 -33-46C. Gibbs 1905 -33-1 C. Brill - 1906 -33-5 C. Perman 1906 -34-6 C. Burrell and Robertson 1916 6. Density of Ammonia Solutions at 15 C. The figures of Lunge and Wiernik (Z. angew. Chem., 2, 181, 1889) are plotted in Fig. 15. The graph gives : (a) percentage NH 3 from specific gravity or from Twaddell degrees ; (b) gms. NH 3 per litre solution from specific gravity ; (c) Ib. of NH 3 per gallon from specific gravity. 7. Solubility of Ammonia at different Temperatures and Pressures. These graphs (Fig. 16) show what weight of NH 3 will dissolve in unit weight of water at tempera- tures from C. to 100 C. under pressures up to 2| atmospheres. Since the heat of solution is great, it is to be understood that the temperatures referred to are final temperatures. 22 8. Freezing Points for various Concentrations of Ammonia. The experimental determinations of F. H. Rupert ( J. Amer. Ghem. Soc., 32, 749) lie very closely on the graph in Fig. 17. 9. Heats of Solution of Liquid and Gaseous Ammonia. Hilde Mollier (Z. Ver. deut. Ing., p. 424, 1909) has measured the heat of solution of 1 kgm. of ammonia when dissolved in various percentage solutions of ammonia. The graph in Fig. 18A explains itself. 10. Heat of Formation of Ammonia from its Elements. Fig. 18B gives Nernst's values of the heat of formation in gm. cals. per gm. mol. at different temperatures. (Nernst, Z. Mectroch., p. 100, 1910). Tamaru (Z. Electroch., 21, 201, 1915^ gives for the heat of formation in gm. cals. per gm. mol. at 1 atm. pressure : Temp. C. 659 554 503 466 Ht. F. 13,100 12,900 12,700 12,670 11. Specific Heats of Anhydrous and Aqueous Ammonia. (a) Anhydrous Ammonia. The following table shows the specific heat of Anhydrous Ammonia at different temperatures TEMP. C. SPECIFIC HEAT. OBSERVER. - 103 to - 188 (solid) 0-50 Dewar. to 26 (liquid) 26 46 0-878 0-894 > Liideking and Starr. 10 1-021 Elleau and Bnnis. 0-876 1 10 1-140 20 1-190 30 40 1-218 1-231 Drewes. 50 1-239 60 ., 1-240 70 1-233 J 20 1-152 "1 Keyes and Babcock. 20 50 1-172 //. Am. Ch. S.,39, 1917. (b") Ammonm Solutions. NH 3 + 31 HoO (3 per cent, solution) NH 3 + 51^0(1-8 ) 101H 2 0(0-9 ) - 18 C. 0-997] . 18 C. 0-999 ^Thomsen. - 18 C. 0-999 J 23 12. Latent Heats of Ammonia. The following table shows the latent heats of fusion and vaporisation of Ammonia in kgm. Calories : LATENT HEAT (KG. GALS.) FOR TEMPERATURE OBSERVER. 1 kgm. J gm. mol. FUSION - 75 C. 108-1 1-84 Massol. VAPORISATION - 33-4 321-3 5-46 Estreicher and Schnerr. - 33-46 341-0 5-81 Franklin and Kraus. 7-8 294-21 5-01 E-egnault. 11-04 291-32 4-961 j- 16-0 297-38 5-064 17-0 296-5 5-05 v. Strombeck. SECTION III. NITRIC ACID DATA. 1. Specific Gravity of HN0 3 Solutions at 15 C. Various observers closely agree. The graph (Fig. 19) has been plotted from Lunge and Key (Z. angew. Chem., 4, 165, 1891). It gives Twaddell degrees, specific gravity, percentage HNO 3 , gms. HN0 3 per litre of solution, Ib. HN0 3 per gall, of solution. 2. Boiling Points of Pure HNO ;5 (99 '79 per cent.) at different Pressures. The data for the graph (Fig. 20) have been taken from Creighton and Grithens (7. I'rankhn Inst., p. 161, 1915). The experimental points lie very closely on the given curve. The graph gives also the total vapour pressure above pure HNO Z at different temperatures. 3. Boiling Points of Aqueous HNO at different Pressures. The data for this graph (Fig. 21) have been taken from the same source as for the preceding graph. 4. Vapour Pressure of Aqueous HNO ;; at different Temperatures. Two graphs (Figs. 22 and 23), plotted from Creighton and Githens' paper, give : (a) total pressure against molecular percentage HN0 3 , and (6) total pressure against percentage HN0 3 by weight. The graphs in Fig. 23 also give the Boiling Points of Aqueous Solutions of HN0 3 at different pressures. 5. Influence of Non-volatile Water-retaining Agents on the Maximum Boiling-point Mixture. Reference : Oreighton and Smith (J. Franklin Inst., p. 703, 1915). The presence of KHSO t produces no change in the position of the maximum boiling-point. The presence of H 2 SO raises the boiling point of HN0 3 solutions and also decreases the HNO^ content of the maximum boiling-point mixture. The decrease is greater the greater the addition of H 2 S0 4 . Diminution of pressure causes a very slight decrease in the HN0 3 content of the maximum boiling-point mixture. The graphs (Fig. 24) are taken from Creightcn and Smith's paper. The percentage HNO 3 refers to dehydrating-agent-free solution. 6. Freezing Points of Aqueous HNO Fig. 25 has been plotted from the determinations of F. W. Kuster and R. Kremann (Zeit. anorg. Chem., 41, ], 1904). 7. Heat of Solution of Nitric_Acid. The following table gives the heat of solution in kgm. Calories when 1 gm. mol. of HN0 3 is dissolved in m gm. mols. of'H 2 0. Thomson's figures are for 18 C. Berthelot's are for 10 C. : m 0-5 1 1-5 2 2-5 8 4 5 6 8 10 20 40 80 100 160 200 320 Thorn. 2-00 3-29 4-16 5-27 5-71 6-66 7-32 7-46 7-44 7-42 7-44 7-45 7-49 Bert. 2-03 3-34 4-16 4-8fi 5-76 6-39jj 6-J6 6-98 7-22 7-27 7-36 7-27 7-21 7-18 Reference : Thomson, Thermochem. Untersuch., Bd. 3. Leipzig, 1883. Berthelot, Ann. Oh. Phys., 5, 4, 468, 1875. 25 8. Vapour Pressures of Oxides of Nitrogen. The experimental data on Vapour Pressures of Oxides of Nitrogen have been plotted in . Figs. 26, 27, and 28, the authors and their papers being given at the head of the graphs. Egerton (Trans. Chem. Soc., p. 652, 1914) states that his results for solid N 2 4 closely follow the equation log p= 14*9166 + 6 (0*0604). The following data concerning the Condensation of Nitrogen Peroxide from Gaseous Mixtures have been deduced from these experimental curves. (a) Condensation of Nitrogen-Peroxide from, a Gaseous Mixture. Fig. 29 has been constructed from the vapour pressure curves of nitrogen peroxide. It shows at what temperatures and (total) pressures condensation should begin for various percentages by volume of peroxide present in the gas. For example, take Curve IV., which is for a 10 per cent. gas. At -- 10 C. condensation will begin at a pressure of 2 atmospheres; any peroxide in excess of 10 per cent, will be liquefied, For the method of construction of these graphs see AMMONIA, p. 19. (6) Percentage of the total Peroxide theoretically removable by Cooling. Two sets of graphs (Figs. 30 and 31) have been constructed from Fig. 29 showing the percentage of peroxide theoretically removable by cooling from a 10 per cent, and from a 15 per cent, mixture at different pressures. The pressure in atmospheres is given by the number on the curve. Example. 90 per cent, removal required from a 15 per cent, mixture : From the curves we see that this can be done (a) at 15 C. by the application of 10 atmospheres; (fe) at 28 C. by 5 atmospheres ; (c) at 36 C. by 3 atmospheres, and so on. For the method of construction of these graphs see AMMONIA, p. 20. 9. The Velocity of Reaction between Nitric Oxide and Oxygen.* This has been experimentally investigated at constant pressure by Lunge and Berl (Z. angew. Ch., 20, 1716, 1907). Their results are given in Fig. 32, which shows the percentage of NO converted at any given time from the beginning of the reaction. It has been found possible to construct general curves for the reaction at constant volume and constant pressure. The following table (see Fig. 32, Curve II.) gives some of the actual experimental values obtained by Lunge and Berl : Initial mixture : 125 cc. NO + 500 cc. Air. Temperature : 20 C. Pressure constant. PERCENTAGE BY VOLUME OF TIME: Seconds. NO. N0 2 . 100- 1-76 47-51 52-49 2-64 38-67 61-33 3-96 . 30-95 69-05 7-92 19-44 80-56 13-78 14-72 85-28 29-92 8-23 91-77 * This subject has been deliberately dealt with in detail in the text partly because of its novelty, and partly in order to render possible its application by the user of the tables to any technical process involving the oxidatiou of nitric oxide. J.A.H. x 12343 26 9. The Velocity of Reaction between Nitric Oxide and Oxygen (continued). At constant volume it is immaterial whether NO 2 or N 2 4 is produced. Fig. 33 gives the velocity of reaction when oxygen is in excess. The presence of an inert gas has very little, if any, effect on the reaction. Fig. 34 is obtained from Fig. 33 and explains itself. The reaction at constant pressure is complicated by volume changes and two sets of curves (Figs. 35 and 36) have been constructed assuming : (a) that the reaction is 2NO -f- O 2 -> 2N0 2 , (6) that the reaction is 2NO 3 + O 2 -> N 2 O 4 . For warm gases at ordinary pressures, when the concentration is small, the tetroxide is practically all dissociated and the reaction may be taken as 2NO -J- 2 * 2N0 2 . Lunge and Berl's Curve I. (Fig. 32) corresponds to p = 8, p being the ratio of the concentration of the O 2 to N0 2 . Curve II. corresponds to p = 1 ' 6. On comparing the sets of curves it will be observed that the reaction is slowest at constant volume and quickest when N 2 4 is formed at constant pressure. The following indicates the method by which the curves have been obtained : 1. CONSTANT VOLUME REACTION. The velocity of reaction is given by dx _ ,, . 3 , dt where a == initial concentration of NO in gm. mols. per litre. x = change in concentration in time t. Since there are 2 molecules of NO in the reaction we take, a = 2 total No. of gm. mols. of NO in 1 litre of the reaction space, while & = total No. of gm. mols. of O t in 1 litre of the reaction space. x b Putting - = X, i.e., the fraction of NO converted, and - = p, we get o/ a dX _ T~I fea 2 (l X)- (p X). k is the velocity constant. Integrating gives lcaH=( X dX ) (I-X)*(p-X)' from which the curves (Fig. 33) have been constructed. (See Todd, Phil. Mag., 35, 281.) 2. CONSTANT PRESSURE REACTION. In this case the volume changes. If the volume of the reaction space at time t is v, then the velocity of the reaction is given by d dt where a is now ^ (total No. of gm. mols. of NO in the reaction space v) t and b = (total No. of gm. mols. of O 2 in the space v), x n (No. of gm. mols. of NO converted), = (No. of gm. mols. of O 2 used up). On putting - = X , the fraction of NO converted vt and = p , we get by a treatment which is too long to be given here : -I dx dX _ X )* (p - X) from which the curves (Figs. 35 and 36) have been constructed. (See Todd, Phil. Mag., 3d, 435.) 27 In this equation I I is the initial concentration, denned as above, of the NO in gm. mols. per litre ; (it \Vo/ corresponds to a in the previous equation). When the reaction is 2NO + O 2 2NO + O s 2N0 2 , = - N 2 4 , a = - . USE OF THE CURVES. (a) To find the Velocity Constant. As an example of the use of the curves let us find the velocity constant &, using Lunge and Berl's Curve L, Fig. 32. At the beginning of the reaction Lunge and Berl had present 125 cc. NO + 500 cc. 2 , i.e., the value of a for NO \Nas 62 '5 cc. per 625 cc. Since 1 gm. mol. occupies 22- 4 litres at C. (say, 24 at Lunge and Berl's temperature) the initial concentration of NO in gm. mols. per litre was 62-5 _ j>25^ I a 24000 "*" 1000 ~ 240 = v 500 Lunge and Berl's Curve I. (Fig. 32) corresponds to p = ^TK = 8 on the theoretical curves. \j O For the reactions 2NO -f 2 - 2N0 2 , and 2NO + 2 -> N 8 4 we get : REACTION. PER CENT. NO CONVERTED. TIME FROM LUNGE AND BERI/S CURVE. YY ( - I t PROM THE w WHENCE * = Seconds. THEORETICAL CURVE. 2NO + O 2 75 1 0-375 21800 -*2N0 2 85 2 0-75 21800 90 3 1-15 22000 94 5 1-95 22400 2NO + 2 75 1 0-370 21300 -HA 85 2 0-67 19200 90 3 1-05 20100 94 5 1-70 19600 Since the product of the reaction at ordinary temperatures is chiefly NOo we will take the velocity constant as k = 22000 (Temp. = 20 C.). (ft) To find the Time required for Oxidation. Let us further illustrate the application of the curves by finding the time required for the oxidation of NO to NO 2 for a definite initial concentration of NO and for various excesses of 2 . Take, for example, the oxidation of NO in the ammonia oxidation process. Suppose that the gas produced after passing through the converter and condensing arrangements consists of oxygen-free nitrogen containing 1 volume of NO in 7 volumes. Let air be admitted for the conversion to N0 2 . Since there is a large excess of inactive gas the reaction may be regarded as taking place at constant volume (Fig. 33). Take p = 1, i.e., just sufficient 2 for complete oxidation. To 7 volumes of gas we must add 2 1 volumes of air, making the total volume 9 ; therefore the initial concentration of NO is a vol. in 9 1 vols., or in gm. mols. per litre a = 24000 I00 = ' 0218 = 2200 x ( ' 0218 ) 2 = 105 . D 2 28 9. The Velocity of Reaction between Nitric Oxide and Oxygen (continued'). 50 For 90 per cent, conversion, kaH = 50 , . ' . t QTJQJJ = 476 sec. = 7 min. 56 sec. Take p = 2 , i.e., add 5 vols. air to 7 vols. gas, a = 24*00 -*- j^Q = 00174 , . . Jca* = 22000 x (0 00174)* = 066 . For 90 per cent, conversion, Fig. 33 gives kaH = 7 ' 5 , 7 '5 t = ~-777>a = 113 sec.= 1 min. 53 sec. O'Ooo 17 For 95 per cent, conversion, JcaH = 17 , . * . t = . = 256 sec - = 4 m i n - sec - Proceeding in the same way we obtain the results in the following table, assuming that initial content of NO = 1 vol. in 7 vols., air is added to convert to N0 3 , temperature = 20 C. : FOR 90 PER CENT. CONVERSION. FOR 95 PER CENT. CONVERSION. Vol. of air added 24 ^=0-36 ? * 1-1 10 1-4 12i 1-8 5 0-71 7 * 1-1 10 1-4 12 * 1-8 Orig. vol. of mixture 7 - 1 1 7 - 1 4 7 - 1 8 7~ 7 - 7 - 7 ~ Time (min.) 7-9 1-9 1-5 T4 1-5 4-3 3-5 3'1 8-3 N.B. It is impessible to get 90 per cent, conversion with a contact time of less than 1'4 minutes ; or to get 95 per cent, conversion with a contact time of less than 3' 1 minutes. For quicker reaction times for the above concentration of NO, pare oxygen would have to be introduced. The calculation of the times of reaction would be done as has been indicated. It should be remembered that the above calculations assume no absorption of the N0 3 produced. In the arc processes the percentage of NO is very low. Assuming the mixture is air containing 2 per cent. NO we have p 19 approximately. The curves in Fig. 33 do not go up to p = 19. but we proceed thus : , 2 , _ = dX 1 a = 100 24000 "* 1000 = 0-00042 p(l-X) X(p- 1) 1 -X ' 1-* / 22000 x (0-00042) 2 = 0' 00388. For 50 per cent, conversion, i.e., X = - 5 kaH = 0*0502 .*. t = 13 '0 sees. For 90 .e. = kaH = 495 /. t = 128 sees. These figures hold good at a temperature of 20 C. The temperature coefficient of the reaction up to temperatures such as are met with in tower practice has not been definitely established, but is probably small. Working on lines indicated in the preceding pages, it has been possible to deduce a general expression for the time of oxidation of nitric oxide in arc gases. The time in seconds required for the oxidation of a fraction X of the nitric oxide present in an arc process gas consisting of air containing P per cent, of nitric oxide is given by ,_ 2-62 x 10 4 /X(200-7P) (200-2P)(1-X)\ (200 -7P)H 6P(l-X) [og ? (200-2P-5X) J when the gases are at a temperature of 20 C. 29 From this expression we get the following table, the results being plotted in Fig. 37 : P = 0*5 per cent. P = 1 per cent. P 1 ' 5 per cent. P = 2 per cenc. jr t (sec.) t (sec.) t (sec.) t (sec.) 0-5 52-9 26-7 17-9 13-5 6 79-5 40-0 26-9 20-4 7 124-0 62-4 41-5 32-0 8 213-0 108-0 72-3 55-1 9 480-0 250-0 164-0 125-0 To be completely general the expression for t should contain a function of the temperature as a factor. No data appear to be available for the determination of this function. F+ 10. Equilibria. The reaction velocity of the reversible reaction A+B+ . . . .^ is given by where C denotes concentration, fej and k z are the velocity constants of the forward and backward reactions respectively. Equilibrium is reached when -.- = 0, at or C x C Y k The ratio -^ = K is called the equilibrium constant. From it is determined the constitution of the /&j equilibrium mixture. It must be remembered that when partial pressures are substituted for concentrations, K may depend on the total pressure. It is much safer to measure concentrations in gm. mols. per litre. K is then only dependent on temperature. In what follows, unless otherwise stated, concentrations in gm. mols. per litre are shown thus [NO], temperatures Centigrade are denoted by , absolute temperatures by T 7 , and logs are to the base 10. XT o 1 9NO -Li oVAl < 6*1.1 \Ja . I -l-^VA) l^i -T7- f. ,,.,-, ^DO = fN7TV lSio #c = 7 -3374--^ [_IN 2 U4,J Reference: Natanson, Wied. Ann. [3], 24, 454,1885; 27, 606, 1886. Bodenstein, ?.'. physik. Chem.,69,43, 1909. Haber (Technical Gas Reactions^) gives at 1 atmosphere pressure : p\ o where K = ec. 18-3 49-9 73-6 99-8 \ 8-06 3-71 1-116 0-544 0-273 30 10. Equilibria (continued). If x = degree of dissociation K = ** ^~ x x T , where P = total pressure in atmos. ^cC Jr* I?orP=l and x = \, then K = 0'865. According to the table, this is for a temperature of approximately 64 C., i.e., N 2 4 is half dissociated at 1 atmosphere at 64 C. (Compare with Fig. 38). Richardson's experimental results (/. Chem. Soc., 51, 402) are given in Fig. 38. 2N0 2 ;2NO + 2 :- . log K. - + 0-75 log T + 4-086. T abs. - 500 600 700 800 900 1,000 *. ' l-32x 10- 6 1-51 X 10- 4 4-55 x 10- 3 5-90 x 10- 2 0-436 2-19 Reference : Bodenstein and Katayama, Z. physik. Chem., 69, 44, 1909. See Fig. 38 for Richardson's experimental results. [NO] 2 [N,] [0 2 ] ; log = log 0249 -2-148 2200 - T tC. - >- 1227 1727 2227 2727 ^ . . . 2-48 x 10~ 3 15-3 x 10~ 3 45-5 x 10" 3 93-0 x 10~ 3 Reference : Nernst, Z. anorg. Chem., 49, 226, 1906. COMBUSTION OF AIR TO NO. In Col. 5 of the following table P TT __ _NO p 4 x p 4 jV a 3 N. = Nernst, Gottinger Nachrichten (1904), p. 261. J. & F. = Jellinek and Finckh, Z. anorg. Chem., 45, 116, 1905 ; 49, 212 and 229, 1906. T abs. Per cent. N 2 Per cent. 3 Per cent. NO. K OBSERVER. 1811 78-92 20-72 0-37 0-0091 N. 1877 78-89 20-69 0-42 J. &F. 2023 0-52-0-80 t) 2033 78-78 20-58 0-64 0159 N. 2195 78-61 20-42 0-97 0242 2580 78-08 19-88 2-05 J. &F. 2675 77-98 19-78 2-23 H 3200 76-60 18-4 5-0 1331 N. 10. Equilibria (continued). 4NH 3 + 50 2 4NO 31 4 6 p X P v so //a J\. = 4 K p X p 6 NH, 0, Partington (The Alkali Industry, 1918, p. 228)i gives 44280 N 2 + 2H 2 O ^ 2NO Reference : 0. F. Tower, Ber. d. ch. Ges., 38, 2945, 1905. 32 SECTION IV. HYDROGEN PURIFICATION DATA. The data contained in this section deal chiefly with those equilibria which form the basis of the more important methods for the technical preparation and purification of hydrogen. The remarks on equilibrium made on p. 29 apply to this section also. 1. Water-gas Equilibrium. [H 2 01 [00] 2170 log K =- ^~ -t- 0-979 log T*- 1-082 x 10~ 3 T + 1-734 X 10~ 7 T 2 - 0-02858. T abs. 1000 1200 1300 1400 1500 1600 1700 1800 1900 2000 K 0-68 1-34 1-73 2-12 2-52 2-92 3-31 3-69 4-07 4-45 Reference : F. Haber, Z. physik. Chem., 68, 731. Figures for lower temperatures calculated from the above formula are given in the following table : t 0. 127 227 327 427 527 627 727 K 0-00049 0-0059 0-031 0-085 0-221 0-369 0-676 These values of K have been plotted in Fig. 39. Abegg (Handbuch der anorg. Chemie) gives : log K= -==jr- 0-0836 log T - 0-00022 T + 2-5084. 2. Carbon Carbon dioxide Equilibrium. Rhead & Wheeler (/. Chem. Soc. 99, 1151) give a modified form of Le Chatelier's formula for the equilibrium constant, namely : ~ 38-055+ 2-02 T- 0-0031 T 2 CJ K=- ~"2T~~ ' + ge + loge ~CT ' where P= total press, in atm., GI = cone, of CQ, C z = cone, of CO 2 , C l + (7 2 = 1. tC. P PER CENT. C0 2 . PER CENT. CO. 800 - 1-23 to 3-05 16 -12 to 28 -40 83-88 to 71-60 900 - 0-65 to 2-90 2-17 to 9-05 97-80 to 90-95 950 - 0-69 to 3-18 1-11 to 4-42 98-89 to 95-58 1000 - 0-66 to 3-78 0-65 to 3-17 99-35 to 96-83 1050 - ... 0-83 to 3-06 0-52 to 1-42 99-53 to 98-53 1100 - 1-33 to 3-64 0-35 to 0-92 99 -65 to 99 -08 33 The effect of pressure on the equilibrium percentage of C0 2 at temperatures between 900 C. and 1100 C. is shown in Fig. 40 taken from Rhead and Wheeler's paper. Boudouard (Ann. Ch. Phys., VIII., 24, 5, 1901) gives the equilibrium percentage of C0 3 as follows : tC 445 650 800 925 Per Cent. C0 2 - 100 61 6-6 4-0 Abegg (Handbuch der anorg. Chemie) gives 9130 log K = rfr where K = Pco, Rhead and Wheeler (7. C. S., 97, 2189) have determined the velocity constants for the separate reactions 2CO -> C0 2 + C and C0 2 -f C -> 2CO. 1 C 1 In the following tables the velocity constant k has been obtained from r log ^ = k. TIME. TEMPERATURE = 850 C. TIME. TEMPERATURE = 850 C. (HOURS.) P at C. P ^co (HOURS.) P at C. P k CO, CO CO 258-6 257-6 463-0 453-7 1 292-3 224-9 0-0590 24 459-2 446-1 0-00030 2 317-8 199-4 0555 48 453-9 435-5 00037 4 356-3 160-9 0511 72 452-1 431-9 30 6 389-0 128-2 0505 96 448-0 423-7 31 8 415-8 101-4 0506 120 447-2 422-1 26 12 439-5 77-7 0434 3. Carbon monoxide Oxygen Equilibrium. _ [CO]* [0 2 ] ~ RT (2 + x) (1 - xf [C0 8 ] 8 According to Nernst and v. Wartenberg (Z. physik. Chem., 56, 548, 1906) log =15-48 - 29600 T 7 + 2-93 log - 1-286 x 10~* (T - 1000) + 1-61 X 10"' (T* - 1000*). The following figures give the percentage dissociation observed by Bjerrum (Z. physik. Chem 79, 1912) : t C. - 2367 2606 2627 2672 2843 Per Cent. 21-0 51-7 49-2 64-7 76-1 x 12343 Haber (Technical Gas Reactions) gives for the most probable values for the percentage dissociation of C0 3 at different temperatures and pressures : T abs. 10 atm. 1 atm. O'l atm. 0-01 atm. 1000 7-31 x 10- 6 1-58 X 10- 5 i 3-4 x 10- 5 7-31 x 10- 5 1500 1-88 x 10- 2 4-06 x 10- 2 8-72 x 10- 2 0-188 2000 0-818 1-77 3-73 7-88 2500 7-08 15-8 30-7 53-0 4. Dissociation of Water Vapour. [0 2 ] . _ _ ~ RT (2 + a?) (1 - a?) 2 ~ [H 2 0] 2 Nernst and v. Wartenberg (Z. physik. Chem., 56, 534, 1906) give OKnqn m log JT e 11-46 =4. 2-88 log -1-38 x 10-" (T - 1000) - 6-85 x 10-8(2* - 1000 3 ). Bjerrum (Z. physik. Chem., 79, 1912) observed the following percentage dissociation at various temperatures : t C. 2027 2369 2425 2488 2561 2656 Per Cent. 2-6 4-3 7-5 8-6 9-8 11-1 Haber (Technical Gas Reactions) gives for the most probable values for the percentage dissociation of H 2 at different temperatures and pressures : T abs. 10 atm. 1 atm. O'l atm. 0-01 atm. 1000 1500 2000 2500 1-39 X 10- 5 1-03 x 10- 2 0-273 1-98 3-00 X 10- 5 2-21 x 10- 2 0-588 3-98 6-46 X 10- 5 4-76 x 10- 2 1-26 8-16 1-39 x 10~ 4 0-103 2-70 16-6 5. Equilibrium between the Oxides of Iron and Carbon. (a) Fe 3 4 + CO 2. 3 FeO + C0 3 . (6) FeO + CO ^ Fe + C0 2 . The equilibrium percentages, by volume, of C0 2 at different temperatures for the equilibria (a) and (6) have been experimentally determined by Baur and Grlaessner (Z. physik. Chem., 43, 358, 1903). The curves given in Fig. 41 are taken from their paper. 35 6. Iron Oxide Hydrogen Equilibrium. 3 Fe + 4H 2 ^ Fe 3 4 + 4H 2 . . The equilibrium pressure of hydrogen at different temperatures is given by Deville {Lieb. Ann., 157, 71, 1871) as follows : Temperature C. 200 265 360 440 765 920 1000 Partial Pressure of H 2 in cms. - 9-59 6-42 4-04 2-58 1-28 0-92 0-51 Preuner (Z. physik. Chem., 47, 385, 1904) gives tG. 900 1025 1150 p(H 2 0) 0-69 0-78 0-86 P(H 2 ) 7. Methane Hydrogen Equilibrium. C. (amorph.) + 2H 3 ^ CH 4 . Abegg (Handbtich der anorg. Chemie) gives log K^^jj - 3-027 log T - 0-0006424 T + 4-617 V '. i *U . > * V . i. < where K = ^p* whence *c. 300 400 500 600 700 800 Per Cent. CH 4 - 96-90 86-16 62-53 31-68 11-07 4-41 Per Cent. H 2 - 3-10 13-84 37-47 68-32 88-93 95-59 Mayer and Altmayer (Ber. Berichte, 40, 2134, 1907) give for 1 atmosphere pressure *c. - 250 450 550 750 850 Per Cent. CH 4 98-79 76-80 46-69 6-08 1-59 Pring (/. Chem. Soc., 97, 509) gives *C. WITH C. WITH C + Ft. 1200 - - 1500 .... 0-35 per cent. CH 4 0-17 ' 55 per cent CH 4 0-30 E 2 36 S. Dissociation of Sulphuretted Hydrogen. 2H 3 S ^ 2Hg -f- Sg. TT - P // ' ~L 7^ (2 X Ps, P 2 H 2 S Preuner and Schupp (Z. phyoik. Chem., 68, 157, 1909) give : *c. 750 830 945 1065 1132 KxW* - - 0-89 3-8 24-5 118 260 p Per Cent. 5-5 8-7 15-6 24-7 30-7 9. Dissociation of Carbon Bisulphide. K =IM < [OS.] ' PC. 823 906 1009 1110 K 0-078 0-115 0-179 0-258 Reference : Koref, Z. anorg. Chem., 66, 88. 37 SECTION V. MISCELLANEOUS DATA. 1. Hydrometer Readings. A graph is given showing the relation between Twaddell and Baume degrees and specific gravity (Fig. 42). Twaddell degrees are a linear function of specific gravity, Baume degrees are not. ! , Twaddell degrees m -,-, n -, onn / i\ sp. gr. = 1 + - - . Twaddell degrees = 200 (sp. gr. 1). 2. Specific Gravity of Solutions at Ordinary Temperatures. The graphs in Fig. 43 give the percentage salt in a solution when the specific gravity is known, (Taken from various sources.) 3. Specific Gravity and Percentage of Salt in Solutions saturated at ordinary Temperatures. (The percentage refers to weight of anhydrous salt in 100 parts by weight of solution.) SALT. Temp. C. Per Cent. Sp. Gr. Tw. Ammonium chloride 15 26-3 1-078 15-5 sulphate 19 50-0 1-289 57-8 Barium chloride 15 25-97 1-283 56-5 Calcium - 15 40-66 1-411 82-2 Magnesium sulphate 15 25-25 1-288 57-6 Potassium chloride - 15 24-90 1-172 34-4 carbonate 15 52-02 1-571 114-0 nitrate - - 15 21-07 1-144 28-8 sulphate - 15 9-92 1-083 16-6 Sodium chloride 15 26-39 1-204 40-8 carbonate 15 14-35 1-154 30-7 nitrate 19-5 46-25 1-380 76-0 sulphate 15 11-95 1-112 22-3 4. Solubilities at Different Temperatures. Graphs are given (Fig. 44) showing the amount of salt which will dissolve in 100 grams of H 2 O at different temperatures. (From various sources.) 5. Vapour Tension of Water at Different Temperatures. The numbers given in Landolt's tables (page 360) have been plotted in Fig. 45. To get the vapour tension in mm. at any temperature, multiply the ordinate by the factor on the curve. 6. Vapour Tension of NaNO. ; and KNO Solutions. The graphs (Fig. 46) show the vapour tension of NaN0 3 solutions for varying concentrations and temperatures. The curves also give the boiling points of the solutions under reduced pressure. 7. Freezing Points. The graphs (Fig. 47) show at what temperature solidification begins for (1) Ca(NO 3 ) 2 and H 2 (2) NH 4 NO 3 and H 2 solutions for various concentrations, and indicate the nature of the solid. 38 FREEZING POINTS OF MIXTURES OF N0 2 AND NO. Percentage by Weight of N0 2 . Nature of Solid. Temperature C. 99-9 1 c - 10-0 91-2 - 18-0 82-9 N0 2 - 31-7 80-0 - 37-7 71-0 1 - 73-0 65-5 N0 2 + NA - 112-5 63-6 1 \r r\ / -108-5 61-3 | JN 2 O 3 | - 104-5 >61-3 8. Heats of Formation. The following table gives the molecular heat of formation, from the elements, in kilogram Calories per gram-molecule, at 15 C. to 20 C. : Mol. H.F. in Kgm. Cals. Mol. H.F. in Kgm. Cals. H 2 liq. - 69-0 NH 4 C1 aq. 72-4 gas - 58-1 (NH 4 ) 2 S0 4 283-0 NH 3 - 12-0 (NH 4 ) 2 S0 4 aq. - 280-6 N 2 - - - - - 19-0 NH 4 OHaq. 90-0 NO - - 21-6 Ca(N0 3 ) 2 - 202-0 NA - - 21-4 KN0 3 119-0 N0 2 (22 C.) - - 1-7 NaOH 102-3 (150 C.) - - 7-6 NaOH aq. - 112-2 N 2 5 liq. - 3-6 NaNO 3 111-0 H 2 S0 4 liq. - 193-0 Na 2 S0 4 - 328-3 HN0 3 aq. - 41-6 Na 3 C0 3 - 272-0 CH 4 21-7 (NH 4 ) 2 S0 3 - - 215-4 CO (from amorph. C.) 29-0 (NH 4 ) N0 2 64-9 '-''-'2 ? 96-9 NH 4 NO 3 - 88-0 C0 2 aq. 102-8 (NH 4 ) 2 C0 3 aq. - 222-0 CuS 10-0 FeO - - - 65-7 Cu 2 S 18-3 Fe 2 3 198-0 CuO 37-2 271-0 Cu 2 40-8 CaO 4 - 140-0 FeS 23-7 9. Heats of Modification-change. The following table gives the heat of change of modification (solid to solid) in kgm. Calories per gm. molecule : Kgm. Cals. NaOH - - 0-990 v. Hevesy. KOH - ------- 1-522 NH 4 N0 3 rhomb-.rhomb (31 to 35 C.) - - -0-402 Bellati and Romanese. rhomb-^rhomboid (82 -5 to 86 C.) -0-427 rhomboid ^regular - -0-950 5 9 9 9 KN0 3 - rhomboid-^prismatic - 1-189 99 99 39 10. Latent Heats of Fusion. The following table gives the latent heat of fusion in kgm. Calories per kgra. and per gm, molecule : LATENT HEAT FOR MELTING POINT. OBSERVER. o p 1 KGM. 1 GM. MOL. \j. (kgm. Cals.). (kgm. Cals.). NH 3 - - - - - 75 108-1 1-84 Massol. Ca(N0 3 ) 2 4H 2 O - + 42-4 33-49 7-94 Pickering. KN0 3 - 339 47-37 4-79 Person. ~ 308 25-5 2-57 Goodwin and Kalmus. KOH - 360-4 28-6 1-61 v. Hevesy. C0 2 (5-latm.) - 56-29 43-8 1-93 Kuenen and Robson. NaOH - ... + 318-4 40-0 1-60 v. Hevesy. NaN0 3 - ... 333 45-3 3-69 Goodwin and Kalmus. HN0 3 - ... - 47 9-54 0-601 Berthelot. H 2 S0 4 - ... + 10-35 24-031 2-358 Pickering. H 2 S0 4 H 2 - 8-53 39-92 4-63 )) N 2 5 - 30 76-67 8-28 Berthelot. N 2 4 .... - 10-14 32-2 2-96 Ramsay. i 11. Latent Heats of Vaporisation. The table gives the latent heat of vaporisation in kgm. Calories per kgm. and per gm. molecule : LATENT HEAT FOR ! VAPORISATION TEMPERA- OBSERVER. TURE. 1 KGM. 1 GR. MOL. "0. (kgm. Cals.). (kgm. Cals.). NH 3 - - - - - 33-4 321-3 5-46 Estreicher and Schnerr. - 33-46 341-0 5-81 Franklin and Kraus. - 7-8 294-21 5-01 Regnault. - - - - 11-04 291-32 4-961 - 16-0 297-38 5-064 17-0 296-5 5-05 v. Strombeck. NH 4 C1. - 350 709-0 37-9 Marignac. HN0 3 .... 86 115-1 7-25 Berthelot. H 2 SO 4 - 326 122-1 11-98 Person. N 2 - 20 66-9 2-94 Cailletet and Mathias. n - - - - 59-5 2-62 .... 20 43-25 1-90 - - 35 9-87 0-43 .... 36-4 o-o o-o NA - 50 44-8 4-84 Berthelot. NA 18 93-5 8-66 Berthelot and Ogier. H 2 (in terms of 15 598-0 10-8 (Mean value). Dieterici, cal.). Henning, Griffiths. 100 539-0 9-67 (Mean value). Joly, Harker, Callendar, Henning, Smith. 40 MISCELLANEOUS CONVERSION TABLES. LENGTH. To convert Multiply by Factor F. Log 10 F. To convert Multiply by Factor F. Log 10 F. Yards to cm. - 91-44 1-9611 Feet to metres - 0-3048 f-4840 Cm. yds. - 0-01094 2-03886 Metres to feet - 3-2808 0-5160 Feet cm. - 30-48 1-4840 Yards to metres 0-9144 1-9611 Cm. ft. - 0-0328 2-5160 Metres to yards 1-0936 0-03886 Inches cm. - 2-540 0-4048 Cm. ins. - 0-3937 1-5952 AREA. To convert Multiply by Factor F. Log 10 F. To convert Multiply by Factor F. Log 10 F. Sq. in. to sq. cm. Sq. cm. to sq. in. Sq. ft. to sq. cm. 6-4516 0-1550 929-03 0-8097 1-1903 2-9680 Sq. cm. to sq. ft. Sq.yds. to sq. m. Sq. m. to sq. yds. 0-001076 0-8361 1-1960 3~-0320 1-9223 0-0777 VOLUME. To convert Multiply by Factor F. Log 10 F. To convert Multiply by Factor F. Log 10 F. Cu. in. to cu. cm. 16-387 1-2145 Pints to litres 0-5682 T-7545 Cu.cm. cu. in. 0-0610 2-7855 Litres pints 1-7598 0-2455 Cu. ft. cu. m. 0-02832 2-4520 Gals. cu. in. 277-41 2-4431 Cu. m. cu ft. 35-314 1-5480 Cu. in. gals. 0-003605 3-5569 Cu. ft. litres 28-317 1-4520 Gals. cu. ft. 0-1605 1-2056 Litres cu. ft. 0-03531 2-5480 Cu. ft. gals. - 6-2290 0-7944 Gals. litres 4-546 0-6576 Litres gals. 0-2200 1-3424 MASS. To convert Multiply by Factor F. Log 10 F. To convert Multiply by Factor F. Log 10 F. Lb. to kgm. Kgm. to Ib. ''- '' Oz. to gins. Gms. to oz. '|*" (| 0-45359 2-2046 28-350 0-03527 1-6567 0-3433 1-4525 2-5475 Grains to gms. - Gms. to grains - Tons to kgm. - Kgm. to tons - 0-0648 15-432 1016-0 0-000984 2"- 8116 1 1884 3-0069 4-9931 41 DENSITY. To convert Multiply by Factor F. Log 10 F. Lb. per cu. ft. to Grms. per cu. cm. gms. per cu. cm. - to Ib. per cu. ft. - 0-016018 62-428 2-2046 1-7954 FORCE. To convert Multiply by Factor F. Log 10 F. Lb. weight to dynes - - 4-45 x 10 5-6482 VELOCITY. Feet per Min. Cm. per Sec. Feet per Sec. Miles per Hour. Metres per Sec. 1 0-5080 0-01667 0-01136 0-00508 1-969 1 0-0328 0-02237 0-0100 60-0 30-48 1 0-6818 0-3048 88-0 44-70 1-467 1 0-4470 196-9 100-0 3-281 2-237 1 RATE OF FLOW. Litres per Hour. Cu. Cm. per Sec. Cu. Ft. per Hour. Litres per Min. Cu. Metres per Hour. Cu. Ft. per Min. Cu.Ft. per Sec. 1 0-278 0-0353 0-0167 o-ooi 0-000588 9-81 X HT 6 3-60 1 0-1271 0-060 0-00360 0-002119 0-0000353 28-32 7-867 1 0-472 0-02832 0-01667 0-000278 60-0 16-67 2-119 1 0-060 0-0353 0-000588 1000-0 277-8 35-31 16-67 1 0-5885 0-00981 1699-0 472-0 60-0 28-32 1-699 1 0-01667 28317-0 7867-0 1000-0 472-0 28-32 16-67 0-2778 101940-0 28317-0 3600-0 1699-0 101-94 60-0 1 x 12343 ENERGY.* Joules. Gm. Cals. Brit. Therm. Units Pound-Deg. Cent. Heat Units Watt. Hrs. Kgm. Cals. H.P.Hours. Kilowatt Hours (B.Th.U.). (C.H.U.). 1 0-2389 0-0 3 9480 0-0 3 5266 0-0 8 2778 0-0 3 2389 0-0 6 373 0-0 6 278 4-186 1 0-00397 0-00221 0-001163 0-00100 0-0 5 156 0-0 5 116 1055 252-0 1 0-5555 0-2930 0-2520 0-0,393 0-0 3 293 1899 453-6 1-800 1 0-5274 0-4536 0-0 S 707 0-0 3 527 3600 860-0 3-413 1-896 1 0-8600 0-00134 o-ooioo 4186 1000 3-968 2-205 1-163 1 0-00156 0-00116 2684000 641200 2545 1414 745-6 643-2 1 0-7456 3600000 860000 3413 1896 1000 860 1-341 1 Heat Emission of 1 gm. cal. per sq. cm. per sec. = 13270 B.Th.U. per sq. ft. per hour. = 7372 C.H.U. Thermal Conductivity. To convert thermal conductivities expressed in C.G.S. units into B.Th.U. per sq. ft. per hour for a fall of 1 F. difference of temperature through 1 in. thickness, multiply by 2903. CALORIFIC VALUE, Grm. Cals. Per Cu. Ft. Pound-Deg. Cent. Heat Units (C.H.U.) Per Cu. Metre. Kgm. Cals. Per Cu. Metre. Brit. Therm. Units (B.Th.U.) Per Cu. Ft. Pound-Deg. Cent. Heat Units (C.H.U.) Per Cu. Ft. 1 0-0778 0-0353 0-00397 0-00221 12-84 1 0-4536 0-0510 0-0283 28-31 2-205 1 0-1123 0-0624 251-9 19-62 8-90 1 0-555 453-5 35-32 16-02 1-8 1 * The subscript figures indicate the number of zeros in the conA'ersion factor given. 43 POWER. RATE OF DOING WORK.* Foot- 1 b. per Min. Egm.- Metresper Min. Watts. (Joules per Sec.). Foot-lb. per Sec. Gram.- Cals. per Sec. Kgm, Metres per Sec. Brit. Therm. Units, (B.Th.U.) per Min. Pound- Deg. Cent. Heat Units. (C.H.U.) per Min. Kgm. -Gals, per Min. Horse- Power. Kilowatts. 1 0-1382 0-02259 0-01666 0-005396 0-002303 0-001285 0-000714 0-0003238 0-0 4 3030 0-0,2260 7-233 1 0-1634 0-1205 0-03904 0-01666 0-009295 0-005164 0-002342 0-0002192 0-0001634 44-26 6-119 1 0-7376 0-2389 0-1020 0-05688 0-03160 0-01433 0-001341 o-ooioo 80-0 8-295 1-3557 1 0-3238 0-1. '$82 0-0771 0-0428 0-0194 0-00182 0-001355 185-3 25-61 4-186 3-088 1 0-4270 0-2382 0-1322 0-0600 0-00561 0-00419 434-0 60 9-806 7-233 2-342 1 0-558 0-310 0-1405 0-01315 0-00981 778-1 107-6 17-58 12-97 4-200 1-793 1 0-556 0-2520 0-0236 0-01758 1400 193-6 31-65 23-33 7-561 3-227 1-800 1 0-4536 0-01244 0-03165 3088 426-9 69-77 51-47 16-67 7-115 3-968 2-205 1 0-0936 0-0698 33000 4562 746 550 178-1 76-03 12-41 23-56 10-69 1 0-746 44260 6119 1000 738 238-9 102-0 56 -88 31-60 14-33 1-341 1 PRESSURE. Dynes per Sq. Cm. Lb. per Sq. Ft. Mm. of Mercury. Feet of Water. Inches of Mercury. Lb. per Sq. In. Metres of Watrr. Kg. per Sq Cm. Atmospheres Tons per Sq. In. 1 0-002089 0-000750 0-0 4 3346 0'0 4 2954 0-0 4 1451 0'0 4 1019 0-0 5 1019 0-0 6 9860 0'0 8 648 478-7 1 0-3591 0-01602 0-01414 0-00694 0-00488 0-000488 0-0 3 172 0-0 4 310 1333 2-785 1 0-0446 0-0394 0-01934 0-1359 0-C01359 0-001316 0'0 5 863 29885 62-43 22-42 1 0-8826 0-4335 0-3048 0-03048 0-02947 0-0 3 193 33850 70-73 25 ' 40 1-133 1 0-4912 0-3453 0-03453 0-03342 0-0 3 219 68920 144-0 51-71 2-307 2-036 1 0-7031 0-0703 0-06804 0-0,146 98060 204-8 73-56 3-281 2-896 1-422 1 0-1 0-09678 0'0 S 635 9806 x 10 2 2048-0 735-6 32-81 28-96 14-22 10-00 1 0-9678 0-00635 1013x10' 2116-0 760-0 33-90 29-92 14-70 10-33 1-033 1 0-00656 1544x10* 3225 x 10 2 1158 xlO 2 5167 4560 2240 1574 157-4 152-4 1 See footnote to page 42. 12313 44 GRAPHS. SECTION L GAS DATA. FIG. 1. AMAGAT'S PV CUBVES FOB HYDROGEN AND NITROGEN. SECTION H. AMMONIA DATA. 2, 3 AMMONIA EQUILIBRIUM, GIVING PEE CENT. NH 3 IN EQUILIBRIUM WITH N 2 -f 3H a AT DIFFERENT TEMPERATURES AND PRESSURES. 4. VAPOUR TENSION OF ANHYDROUS AMMONIA AT DIFFERENT TEMPERATURES. 5, 6. TEMPERATURE AND PRESSURE AT WHICH AMMONIA BEGINS TO CONDENSE FROM A GASEOUS MIXTURE. 7, 8, 9. REMOVAL OF AMMONIA FROM GASEOUS MIXTURES BY COOLING AT PRESSURES OF 50, 100, 150 AND 200 ATMOSPHERES. 10 VAPOUR PRESSURE OF AMMONIA SOLUTIONS AT DIFFERENT TEMPERATURES. 11. PARTIAL PRESSURES OF NH 3 AND H 2 O ABOVE AMMONIA SOLUTIONS. 12. PARTIAL PRESSURES OF H 2 O ABOVE AMMONIA SOLUTIONS. 13. PARTIAL PRESSURES OF NH 3 ABOVE AMMONIA SOLUTIONS. 14. DENSITY OF LIQUID AMMONIA AT DIFFERENT TEMPERATURES; ALSO THE DENSITY OF THE SATURATED VAPOUR OVER LIQUID AMMONIA. 15. SPECIFIC GRAVITY OF AMMONIA SOLUTIONS AT 15 C. 16. SOLUBILITY OF AMMONIA AT DIFFERENT TEMPERATURES AND PRESSURES. 17. FREEZING POINTS OF AMMONIA SOLUTIONS. ISA. HEAT OF SOLUTION OF LIQUID AND GASEOUS AMMONIA. 18s. HEAT OF FORMATION OF AMMONIA. SECTION m. NITRIC ACID DATA. 19. SPECIFIC GRAVITY OF NITRIC ACID SOLUTIONS AT 15 C. 20. BOILING POINT OF PURE NITRIC ACID AT DIFFERENT PRESSURES. 21. BOILING POINTS OF AQUEOUS NITRIC ACID UNDER DIFFERENT PRESSURES. 22, 23. VAPOUR PRESSURE OF AQUEOUS NITRIC ACID AT DIFFERENT TEMPERATURES. 24. INFLUENCE OF H 2 SO 4 ON THE BOILING POINT OF AQUEOUS NITRIC ACID. 25. FREEZING POINTS OF AQUEOUS NITRIC ACID. 26. VAPOUR PRESSURES OF N 2 O 3 AND N 2 O 4 . 27. VAPOUR PRESSURE OF SOLID N 2 O 4 . 28. VAPOUR PRESSURES OF NO AND N 2 O. 29. TEMPERATURE AND PRESSURE AT WHICH NITROGEN PEROXIDE BEGINS TO CONDENSE FROM A GASEOUS MIXTURE. 30. REMOVAL OF NITROGEN PEROXIDE FROM A 15 PER CENT. GASEOUS MIXTURE BY COOLING AND PRESSURE. 31. REMOVAL OF NITROGEN PEROXIDE FROM A 10 PER CENT. GASEOUS MIXTURE BY COOLING AND PRESSURE. 32. VELOCITY OF OXIDATION OF NITRIC OXIDE AT CONSTANT PRESSURE. 33. TIDSORETICAL CURVES FOR THE OXIDATION OF NITRIC OXIDE AT CONSTANT VOLUME. 34. FURTHER CURVES DEDUCED FROM FIG. 33. 35, 36. THEORETICAL CURVES FOR THE OXIDATION OF NITRIC OXIDE AT CONSTANT PRESSURE. 37. TIME OF OXIDATION OF NITRIC OXIDE IN AIR MIXTURES. 38. DISSOCIATION OF NITROGEN TETROXIDE AND OF NITROGEN PEROXIDE. SECTION IV. HYDROGEN PURD7ICATION DATA. 39. WATER-GAS EQUILIBRIUM. 40. DISSOCIATION OF CARBON MONOXIDE : EFFECT OF PRESSURE ON THE EQUILIBRIUM PERCENTAGE OF CARBON DIOXIDE IN THE PRESENCE OF CARBON. 41. OXIDES OF IRON OXIDES OF CARBON EQUILIBRIA. SECTION V. MISCELLANEOUS DATA. 42. SPECIFIC GRAVITY FROM HYDROMETER READINGS. 43. SPECIFIC GRAVITY OF SALT SOLUTIONS. 44. SOLUBILITIES AT VARIOUS TEMPERATURES. 45. VAPOUR TENSION OF WATER AT DIFFERENT TEMPERATURES. 46. VAPOUR TENSION OF NaNO 3 AND KNO 3 SOLUTIONS AT DIFFERENT TEMPERATURES. 47. FREEZING POINTS OF SOLUTIONS OF Ca(NO 3 ),i AND NH 4 NO 3 . 45 INDEX. PAGE. FIG. AlR: combustion of, to NO - - - - - - - . --30 density of- ......... g ratio of specific heats of- ....... - 14 specific heats of - --..... 11 thermal conductivity of- ...... ..16 viscosity of ........ - 9 AMAGAT: PV cm-ves for hydrogen and nitrogen .......51 AMMONIA : anhydrous, density of - ----- 21 14 melting and boiling point - ..... 21 specific heat of ....... 22 vapour pressure of - .... 19 4 condensation, from gaseous mixtures - ----- 19 5, 6 data . 18-23 equilibrium .... _.._]8 ,, effect of pressure and temperature on 18 2,3 heat of formation of ....... 22 18B solution of ....... 22 18A latent heats of- ........23 -oxidation equilibrium - - - - - . . . . -31 partial pressure of, in solutions - - - - - - - - -21 12 removal by cooling and pressure - - - - - . - 20 7, 8, 9 solubility of -------- 21 16 solutions : freezing points of - ........ 22 17 specific gravity of - - - - - - - - - 21 . 15 specific heat of- - - - - . . - - -22 vapour pressure of- - - - - - - - -20 10 AMMONIUM NITRATE SOLUTIONS, freezing points of - - - - 37 47 AREAS, conversion factors for - - - - . . . -40 ARC PROCESS GASES, oxidation of NO in - - - - - - 28 37 BAUME HYDROMETER READINGS - ....... 37 42 BOILING POINT OF : anhydrous ammonia - - - - - - - 21 aqueous nitric acid, effect of H 2 SO.i on - - - - - 24 24 ,, ,, variation with pressure - 24 21 (HNO :j ) mixture, maximum - - - - - - - 24 24 pure nitric acid : variation with pressure - - - - - - - -24 20 BOYLE'S LAW, deviation of gases from - - - - - - ..5 BRITISH THERMAL UNIT (B.TH.U.), conversion factor? for - - - - - 42 CALCIUM NITRATE SOLUTION, freezing points of - - - - - - 37 47 CALORIE, conversion factors for - - - - - - -42 CALORIFIC YALUES, conversion factors for - - - 42 CARBON : bisulphide, dissociation of .... 36 carbon dioxide equilibrium - - - 32, 33 ,, , effect of pressure on 33 40 dioxide, dissociation of ... . 33, 34 under high pressure ... 5 monoxide oxygen equilibrium - 33 oxides iron oxides ,, ....... 34 41 COMBUSTION : heats of ' - - - - 38 of air to nitric oxide .... 30 COMPRESSION OF GASES ... - 5, 6 CONDENSATION : of ammonia from a gaseous mixture - 19 5-9 nitrogen peroxide from a gaseous mixture - 25 29-3 CONDUCTIVITY, thermal, of gases - 15 U 2 46 PAGE. FIG. CONVERSION TABLES - CRITICAL CONSTANTS - - 7 CYLINDERS : capacity of, for different gases to fill, with N 2 + 3H 2 mixture at high pressure - DENSITY : conversion tables for of anhydrous ammonia ,, aqueous ammonia nitric acid ,, ,, solutions ,, gases - nitrogen peroxide at different temperatures DILUTION, heat of : of ammonia . - 1 A nitric acid DISSOCIATION OF : ammonia - 2, 3 carbon bisulphide - dioxide -- ...... - 33, 34 nitric oxide nitrogen peroxide tetroxide sulphuretted hydrogen water vapour EMISSION OF HEAT - ENERGY, conversion tables for EQUILIBRIA EQUILIBRIUM OF: ammonia in N 2 + 3H 2 mixture - carbon carbon dioxide - - - 32, 33 40 carbon monoxide oxygen carbon oxides iron oxides carbon sulphur - nitric oxide oxygen nitrogen oxygen 30 FLOW OF GASES THROUGH PIPES - 10 FLOW- BATES, conversion tables for FORCE, conversion tables for - FORMATION, heats of - FREEZING POINTS of ammonium nitrate solutions - calcium nitrate solutions - 47 ,, anhydrous ammonia ,, aqueous ammonia 22 ,, nitric acid - 24 25 ,, N0 2 and NO mixtures - GAS: cylinders, capacity of, for different gases data - 5-17 flow through pipes 10 GASES : density of - specific heats of - - 11 thermal conductivity of - 15 under pressure - 5 viscosity of HEAT: conductivities of gases -- -- - - 35 of formation of ammonia - - 22 18B ,, solution ,, 22 ISA nitric acid - - - - - - - - -24 PAGE. FIG. HEATS, latent, of : ammonia - ------ -23 fusion . . . . 39 vaporisation - .....39 of formation - . . - . . -38 of modification-change - ........38 specific, of: ammonia ...........22 gases . . - 11 HORSE-POWER : conversion factors for - - -...43 -hour, conversion factors for - ...... 42 HYDROGEN : at high pressure - ... 5 deviation of, from Boyle's law - - ... 5 methane equilibmim - ... 35 -nitrogen mixture N a + 3H 2 : at high pressure - 6 conductivity of - . - 17 specific heat of - - - - 13 viscosity of 10 purification data - - - 32 PV curves for - - 1 HYDROMETER READINGS - - 37 42 ICE, vapour pressure of - 45 IRON OXIDES : carbon oxides equilibrium - - 34 41 hydrogen equilibrium - - - - - 35 JOULES, conversion factors for - 42 KILOWATTS, conversion factors for - - 43 LATENT HEATS: of ammonia ........ - - - 23 of fusion - - ........ 39 of vaporisation ---....-..-39 LENGTHS, conversion tables for - - 40 MASS, conversion tables for -- -- ...-40 MAXIMUM BOILING POINT (HNO 3 ) MIXTURE 24 ,, , influence of water-retaining agents on - 24 24 MELTING POINT or: anhydrous ammonia - - 21 aqueous ammonia ------ -..--22 17 aqueous nitric acid .... ......24 25 MELTING POINTS ..... ... 39 METHANE HYDROGEN EQUILIBRIUM 35 MISCELLANEOUS DATA - 37 NITRIC ACID, aqueous : specific gravity of - - 24 19 boiling points of - - ... 24 21 effect of H 2 SO 4 on boiling point of - 24 24 freezing points of - 24 25 maximum boiling point mixture - 24 24 vapour pressure of - 24 22, 23 data ... . .... 24-31 heat of solution of 24 pure : boiling point - 24 20 vapour pressure - 24 20 NITRIC OXIDE: combustion of air to 30 dissociation of- - - - - - - - - - -30 48 NITRIC OXIDE (cont.) oxidation of .... ,, , at constant volume , at constant pressure , time of - ... , time of, in arc gases NITROGEN : Amagat's P V curves for - ... deviation from Boyle's law ... -hydrogen mixture. (See Hydrogen- Nitrogen mixture.) -peroxide : condensation of, from a gaseous mixture - . - density of, at different temperatures dissociation of ..... removal by cooling and pressure - - specific heats of - ..... -tetroxide, dissociation of - - - . . thermal conductivity of - ' - viscosity of ... OXIDATION OP NITRIC OXIDE. (See Nitric Oxide) - . - OXIDE OF IRON HYDROGEN EQUILIBRIUM - OXIDES OF IRON OXIDES OF CARBON EQUILIBRIUM OXIDES OF NITROGEN : heats of formation of - ' latent heats of fusion of - .... ., vaporisation of - vapour pressure of - . . . . PARTIAL PRESSURE OF: ammonia above its solutions - ^ water above ammonia solutions - ... PEROXIDE OF NITROGEN. (See Nitrogen Peroxide) PIPES, note on flow of gases through - POUND-DEGREE-CENTIGRADE HEAT UNIT (C.H.U.), conversion factors for POWER, conversion tables for ------ PRESSURE : conversion factors for - - - critical, of gases - ... effect of, on : ammonia equilibrium . . . . boiling point of nitric acid - - - - condensation from gaseous mixtures solubility of ammonia - specific heat of gases .... vapour. (See Yapour Pressure) - RATE OF OXIDATION OF NITRIC OXIDE - ... RATIO OF SPECIFIC HEATS OF GASES REMOVAL BY COOLING AND PRESSURE: of ammonia - of nitrogen peroxide - SOLUBILITIES AT DIFFERENT TEMPERATURES - - f i SOLUBILITY OF AMMONIA - . *'-' . , SOLUTION, heat of : of ammonia of nitric acid SPECIFIC GRAVITY OF: ammonia solutions - - anhydrous ammonia . aqueous nitric acid solutions (saturated) ....... PAGE, FIG. 25 26 33, 34 26 32,35,36 27 28 37 25 29 8 30 38 25 30, 31 12 29 38 16 9 25-30 35 34 41 38 39 39 25 26-28 20 11,13 20 11, 12 3, 25, 30 10 42 43 43 7 18 2,3 24 20, 21 19, 25 5,6,29 21 16 11-15 27 32 14 20 7, 8, 9 25 30,31 37 21 44 16 22 ISA 24 21 21 24 37 37 15 14 19 43 49 SPECIFIC HEAT OF: 1>AGE ammonia solutions ---.....22 anhydrous ammonia ---..... at constant pressure - ------ II volume - --------12 N 2 + 3H 2 mixture - ---.-..13 variation of, with pressure - . . . . . . -11 13 ,, temperature - - - - - . . -12 SPECIFIC HEATS, ratio of - - - . . . . . . - 14 SULPHURETTED HYDROGEN, dissociation of - - - . . . . - 36 SUTHERLAND'S FORMULA FOR YISCOSITY OF GASES . ' ... . . . - 9 TEMPERATURES, critical, of gases - - . . . . . . .7 TENSIONS OF AQUEOUS VAPOUR - ....... 37 45 THERMAL CONDUCTIVITY : conversion to B.Th.Us. and C.H.Us. - -. . . . . -42 of gaseous mixtures .........17 oi gases ------.../.. 15 of N 2 + 3H 2 mixture - - - - . . . -17 THERMOCHEMISTRY - . . . . . - 33, 39 TIME REQUIRED FOR THE OXIDATION OF NlTRIC OXIDE - - - - 27 TWADDELL HYDROMETER HEADINGS - - - - - . - 37 42 USEFUL NUMBERS AND CONVERSION TABLES - - - - - - 40 VAN DER WAALS' : constants - ......7 equation - .......7 VAPORISATION, latent heats of ...... 39 VAPOUR PRESSURE OF : ammonia solutions - - - - - 20 10 anhydrous ammonia - - - - 18 4 ice 45 niti'ic acid (aqueous) - . - - 24 22, 23 (pure) - - 24 20 nitric oxide - - - - - - - - - - 28 nitrogen tetroxide - - - - 26 (solid) - - 25 27 trioxide - ... 26 nitrous oxide - - 28 potassium nitrate solutions - 37 46 sodium - 37 46 water . 37 45 VELOCITY : conversion factors for - .... 41 of oxidation of nitric Oiide - 25 32 VISCOSITY OF GASES - 8 ,, Sutherland's formula - 9 VOLUME : conversion factors for - - 40 critical, of gases -- - ... ..7 WATER-GAS EQUILIBRIUM - 32. 39 WATER VAPOUR: dissociation of- - - - - - - - - - -34 tension of - - - 37 45 WATTS, conversion factors for - - - 43 WATT-HOURS, conversion factors for - - - - 42 CO UJ o: ID co a cc QL 08 CO LU < o: u Q. s LU UJ cr UJ u. LJL UJ CD O OC Q z LJ CJ) O QC CC O u. K< 2 DC UJ X a CO o z D. (VI Ad FIG. 2. AMMONIA EQUILIBRIUM. FOR N 2 + 3 H 2 + AMMONIA MIXTURE ONLY. 20 40 60 80 100 120 140 160 180 ZOO 220 240 260 280 ATMOSPHERES. 9S9B. MalbyA.3ons.UtK FIG.3. AMMONIA EQUILIBRIUM. THE NUMBERS ON THE GRAPHS GIVE THE PRESSURE IN ATMOSPHERES. (Based on Habers Figures * 400 ssaa. nnilisa 500 600 700 800 TEMPERATURE C. 900 . MalbviS.ins.Litl. \ o o 00 o CD ^ CO o 00 QL & UJ H R 9 N" Nl o 3898 TEMPERATURE* PRESSURE AT WHICH CONDENSATION SHOULD JUST BEGIN FOR PERCENTAGES OF NH 3 (BYvot.) UP TO 1-0%. CALCULATED FROM VAPOUR PRESSURE DATA. FIG.6. ZO 40 6O 80 100 120 140 !6O ISO 200 220 240 260 280 300 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 ATMOSPHERES. > MalbyiSons.lith G3AOW3a e HN 1V101 JO % REMOVAL OF NH 3 FROM GASEOUS MIXTURES BY COOLING AT 150 ATMOSPHERES. (From vapour pressure data) 100 Q UJ UJ oc g 4O 30 -60 -50 -4-O -3O -2O TEMPERATURE 'C -10 THE CONTENT OF NH 3 (%BY VOL) IS GIVEN ON THE CURVES. THE ORDINATES GIVE % OF NH 3 CONTENT REMOVED. 3696. nm/IS3. Malbyi.Sons.Lith o u_ o 2C -J O o o Hi g UJ oc. Q. UJ to UJ to CO UJ cc o. to o 1 1V101 JO 7. o LU O UJ Z O o ce u_ o 3= to C o CO UJ ID O UJ UJ o UJ a: UJ a: => CO to UJ to o 1 o o o o UJ a: a: UJ Q. S UJ O DC eO CO I O I I I Q3AOW3M E HN 1V10JL dO % S3a3HdSowiv NI 3anss3Hd FIG.H CO o O CO 520 480 440 130 400 UJ 360 Pis. CO UJ QC jo <0 DC LJ 0. z UI I- z u UJ 320 280 3 tn to UJ ct OL _l I 5 10 15 /. NH 3 IN SOLUTION^BY WEIGHT) 20 Malby &Sons.Lith. N1 OH JO 3MnSS3d IVIlHVd NI O'H jo 3anss3yd FIG. 13. PARTIAL PRESSURE OF NH, ABOVE TS SOLUTION NUMBERS ON GRAPHS GIVE%NHJN THE SOLUTION 20 10 10 20 30 TEMPERATURE^ i-D -b IV 831VM (3/\yno Q31VWniVS JO A1ISN3Q CD DENSITY OF LIQUID AMMONIA AT DIFFERENT TEMPERATURES. J.ANGE I898 DIETERICI 1904?*" tfJOiOOiOOiOO m O JQ O O *d" *j" OQ CO CM CM O Pop ppppppp p p ) 10 20 30 40 50 60 70 80 90 100 TEMPERATURES. -^, */ / n , nn (SEE LANDOLTP.I52) x ^ H % , s / ^ \ s \ / ' 1 \ \ \ \ \ \ v J \ \ i i i \ i t i t t w O i O cv i CO / / / / o r iO o 5 J* > ^ * > } O IO O IO O LO O IO C > 10 o

CVJ 6 (aA^ino snonNi.i.NOo)^HN QinbH JO AISN3Q c c D > ) ( L c M o NOli rnos '3^J .n Jd r O in oo \ 1 1 I i 1 I op OJ K i l /T"v ] \ \ N I < r OD i \ \ l -+ t 1 h O 1 k \ *~~\ * 1 t * JLl J3 7- 9 CO \ ' 4 D .J ?: 1 \ \ C 1 D r JU 9 CD 3 ! \ 9 ^ \ CO 1 s \ 9 C\J t i 1 < i r> D 9 i D -J "\ I IT x. k i^> J < /> if I X \ \ 9 i i_ < z: Ju l - 1 1 1 n 3 \ CD I j >- I > - i ii. \ 0) i 4 t > < y 1 1 5 1 i. 3 \ V u> 1 ( ( J) > ( r 1 \ 9 \ J_ 1 1 s> D _J \ CO 1 [ t J Jj 1. !\ s k 9 < /) \ \ CD fVk N i \ 6 \ Io o O C R ; t- c\ cr J ) C rf ) > OC rv ) 1 cc ex -d Cv ; cv 1 CN. C 1 C\ > ec i - > a . ^ > x t ! 9 > a ) cr > ^ IV 1 C 1 Fl SOLUBILITY OF AMMONIA IN H 2 AT DIFFERENT TEMPERATURES & PRESS (See Caste//- Evans,H p. IO02) 100 200 300 400 500 GOO 700 800 900 1000 1100 IZOO 1300 1400 1500 1600 !700 1800 1900 PRESSURE IN mm. 98911. MalbyA.Sons.Utl % NH, FIG. 17. 10 ZO 30 40 50 60 70 80 90 100 FREEZING POINTS FOR VARIOUS CONCENTRATIONS OFAMMONIA IN H 2 0. F.H.RUPERT. J.AMER CHEM.SOC.3Z.749. \/ 10 20 30 50 60 70 80 90 100 NH IN SOLUTION. 9 9B9B Malby&Sons.Lith. HEAT OF FORMATION OFNH 3 FROM ITS ELEMENTS. NERNST. Z.ELECTROCHEM.I9IO.P.IOO. o o g o o 0) o c 00 o R O 8 O O in o s o o CO o N O o / r ( ^^. V> X \ \ \ \ V \ \ v X o o o o o o o o o o o o O ta Q tf) O IT !> ^ 3 2 <2 Si o o . ui o: 1 DC UJ Q. S UJ f- in m o m in o ^ CO O CO U) C\J o CJ in O o CO i" cr UJ 5 U) 2 g N -L IX ^ 00 s g o to CO = < ^- P - 2 S s h- < 5: < CD ^ s s ? o < H * a o m 100 2- TWADDELL DEGREES. FIG. 19. 10 SPECIFIC GRAVITY OF HNO SOLUTIONS AT I5C. LBS. PER GALL- rfe (GMS. PER LITRE) FROM LUNGE & REY. Z.ANGFW CHEM.4. 165 . 1891. 100' 05 I 10 15 1-20 25 130 35 SPECIFIC GRAVITY- 140 45 50 5S MaJby&Sons titfi. FIG. 20. \ en or X tJL o CO LU a: LU cc Q_ h- z: LU O CL ! O 03 *3 CJ o ^ to -^ ^ ^ ^ ^ u3 9 I < 3- "8 O 00 O CD O <* O CO 'OoiNIOd Malby^Sons.Lith. CVJ O (WWNI) 3anSS3Hrf FIG. 23. LU < a: LU a. S LU LU CSL LU LL LL 5 ro O O to t/D Z3 O LU => Of < u_ o z: o CO z LU h- O a_ J- CO m O 'SN31 dVA INFLUENCE OF H 2 S0 4 ONTHE BOILING POINTS OF AQUFCUS HN0 3 CREIGHTOH& SMITH J.FRAN KLIN INST. 1915 P. 706. FIG. 24. 70 30 40 50 60 %HN0 3 (BYWT.) 70 80 to CM I-' > DO CO O z 1C o o 00 o h- O O CO O O U) O O o o CVJ o o \; At \ V o\ T\ V o CO o o 5 H- :,< Ul 1- C5C O X o r- O co g ,G ^^ "f ^v. 8 o un o CVJ O CM o O V I \ \ x T o 9 O a r o cu O oo ^ > "^ ^- LU CO D O UJ CO CD UJ a: D CO CO UJ a a a: CJ o ii. o o E UJ UJ (T D UJ DC a S O o: LL Q UJ D O _I < O <0 o OOQO ooooo a3AOlAI3d 6 ONJO CVJ CO O Noiiovaa 3H.L yod (SQNOOSS NI) j. aw o CO o CVJ 10 < LU CSC LU X H LL O 1- o o _l 111 2 NO 2 NO 0) CD h- X UJ CD U U) -1- + z. z LU CQ 111 CD Z D _J o o U} OJ o" o LO CM o o cva U 3 P CO c_ Q> 0. E \ o 05 o 00 70 GO 50 4-0 3O 20 J I i> a s NO (BY VOLUME) CONVERTED TO CO O u_ z Ui o 3: p LU O X Q a: LJL O z o O a: a u o 3 O LU O o ca O M ~ -X -C *J O c b o iO 9. CO a -X in m ol <- 22 ^ O O Z O CO O CO h Q - \ \ "g 05 I ? < O CO (0 8 O o LO o 5 o o o N n ^-^ o "^, ^V 00 1 x Sv o R N r. ui s^ I- >y < + O \ tfi O w K ZK <^ CO CO *> Co 1L . O N * ^ z z - ; 2 t* 5 Si |1 c3 - | ^ 8 5 o O cj * 2 xo ^ CO ~^s \ \ \ Q Q (/) U \ a \ CO V Q \ o o CO 10 OOQOO F!G.-4O. DISSOCIATION OF CARBON MONOXIDE (at temperatures indicated ) 2 CO ^ CO 2 + C. Rhead & Wheeler. J.C.S. 99. i/SI, 3898. MalbyiSons.Lith FIG. 4-1. EQUILIBRIA BETWEEN OXIDES OF IRON AND CARBON. Fe O + CO ^ Fe + C O 2 5OO 6OO 7OO 8OO 9OO IOOO TEMPERATURE C. 80 Fe 3 O 4 +CO ^ 3FeO + CO 2 N Oeo O 50 \ 3OO 4OO 5OO 6OO 7OO TEMPERATUREC. 8OO 9OO MalbyA.Sons.Lith. YE I i 390