EXCHANGE -L/ cr The Hydration of Sodium Monometaphosphate to Orthophosphate in Varying Concentrations of Hydrogen Ion at 45 Centigrade . OP 7 A DISSERTATION Submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in the Faculty of Pure Science of Columbia University. BY SAMUEL J. KIEHL, A. B. NEW YORK CITY 1921 The Hydration of Sodium Monometaphosphate to Orthophosphate in Varying Concentrations of Hydrogen Ion at 45 Centigrade DISSERTATION Submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in the Faculty of Pure Science of Columbia University. BY SAMUEL J. KIEHL, A. B. NEW YORK CITY 1921 DEDICATED TO LOUELLA SOLLARS KIEHL, my wife, whose sympathetic interest has been an inspiration. ACKNOWLEDGMENT. To Professor Hal Trueman Beans at whose sug- gestion this problem was undertaken, the author wish- es to express his sincere thanks for helpful guidance constantly received throughout the progress of the entire investigation. THE HYDRATION OF SODIUM MONOMETAPHOS- PHATE TO ORTHOPHOSPHATE IN VARYING CONCENTRATIONS OF HYDROGEN ION AT 45 CENTIGRADE. The hydration of metaphosphoric acid to orthophosphoric acid or a metaphosphate to the orthophosphate, as NaPO 3 + H 3 O - NaH 2 PO 4 , has attracted the attention of chemists ever since the epochal work of Graham 1 . Much work has been done but the problem is not completely solved. Graham was aware of some of the difficulties to be encountered. In his work he states, "The problem is therefore environed with difficul- ties." These difficulties seem to be twofold : First, metaphos- phoric acids or their salts are not well understood. It is known that polymers exist the preparation of which has not been thoroughly investigated and the decision as to their forms has been based mainly upon their methods of preparation or empirical formulae rather than upon experimental evidence. Different polymers present different problems of hydration. Second, the rate of hydration must be ascertained by the meas- urement, at intervals, of either the concentration of the meta- phosphate left unchanged in the solution or the concentration of the orthophosphate formed during the progress of the reac- tion. On account of the widely differing solubilities of the polymeric forms of the metaphosphates, the direct determina- tion involving an actual separation of the orthophosphoric acid from the meta is by no means easy, especially when pyrophos- phoric acid is formed as an intermediate product. This sepa- ration is actually necessary in order to study the factors influ- encing the hydration. So to understand better this reaction the two above men- tioned difficulties must be overcome as far as possible. This requires, as a basic consideration, that a definite polymer be prepared and its hydration studied. Furthermore, the definite polymer must be readily and quantitatively separable from the substances formed during the hydration. Phil. Trans. 123,53 (1833). Heretofore the methods employed in the study of the hy- dration of metaphosphoric acid have been mostly indirect, and the acid used was prepared either by dissolving phosphorus pentoxide in cold water or by dehydrating orthophosphoric acid or by preparing a heavy metal salt from which a solution of the meta acid was obtained upon the withdrawal of the metal by hydrogen sulphide. Acidimetry was used by Sabatier 1 , Monte- martinie and Egid 2 , Bertholet and Andre 3 , and BalarefP ; ther- mochemistry by Giran 5 ; gravimetric analysis by Holt and Meyers 6 ; change of index of refraction by Blake and Blake 7 ; change of conductivity by Prideaux 8 ; and change of the lower- ing of the freezing point by Holt and Meyers 9 . In their gravimetric method Holt and Meyers precipitated the unchanged metaphosphate in the presence of ortho and pyro as a barium metaphosphate bearing the empirical formula Ba(PO 3 ) 2 . By repeated experiments with mixtures of ortho, pyro, and meta they claim very little variation in the composi- tion of their precipitate. However, the result they obtain in the measure of the actual hydration is the best criterion of the trustworthiness of their method. Judging from the irregu- larity of the curve they publish it seems that their method is open to question or fraught with a considerable error. Other attempts to apply methods, of precipitation were employed to show whether or not pyrophosphoric acid was formed during the process of hydration 10 . Neither method is applicable to the problem. Because on the one hand, the method of Bertholet and Andre requires the heating of the solution to be analysed acidified with acetic acid on a boiling water bath for three or four hours to secure the formation of an uncertain magnesium ammonium pyro- 1 Compt rendu 106, 63 (1888), 108, 734 and 804 (1889). 2 Gazz. Ital. Chim. 31, 1, 394 (1901). 3 Compt. rendu 124, 261 (1897). * Zeit. Anog. Chem. 72, 85 (1911). 3 Compt. rendu 135, 1333 (1902). 6 J. S. C. Trans. 99, 384 (1911). 7 Am. Chem. J. 27,68(1902). s -Chem. News 99, 161! (1909). 9 J. C. S. Trans. 99, 385 (1911), 103, 532 (1913). 10 Balareff, Zeit. Anorg. Chem. 68, 266 (1910). Bertholet and Andre, Compt. rendu. 124, 261 (1897). 8 phosphate, a treatment entirely out of the question in view of the marked effects of temperature and hydrogen ion upon the rate of hydration. On the other hand the precipita- tion of pyrophosphate of copper or cadmium in an acetic acid solution, the method employed by Balareff, is open to question because upon it he based his contention that no pyrophosphate as an intermediate product was formed during the hydration, a statement not in harmony with his later work 1 . There have been two different opinions as to whether pyro- phosphoric acid was formed as an intermediate product during the hydration of metaphosphoric acid to ortho. One group of chemists maintained that the hydration was direct to ortho, while another claimed pyrophosphoric acid as an intermediate product. The former was supported by Graham 2 , Sabatier 3 , Montemartini and Egid 4 , and Balareff 5 ; while Bertholet and Andre 6 , Giran 7 , Holt and Meyers 8 , and Balareff 9 adhered to the latter. Accordingly a method has been devised and materials pre- pared for the attack of this problem whereby the conditions and factors influencing the reaction may be studied to a better ad- vantage by direct standard analytical methods. An account of the investigation will be presented under the following head- ings : Apparatus, Preparation of Materials, Method of Pro- cedure, Experimental Data, Discussion, and Summary. 1 Zeit. Anorg. Chem. 96, 103 (1916). 2 Phil. Trans. 123, 53 (1833). 3 Compt. rendu. 106, 63 (1888). 4 Gazz. Ital. Chim. 31, I, 394 (1901). 5 Zeit. Anorg. Chem. 67, 234 (1909) ; 68, 288 (1910). 6 Compt. rendu. 123, 776 (1896) ; 124, 265 (1897). 7 J. Russ. Chem. Soc. 30, 99. 8 J. C. S.Trans. 99,385 (1911). 9 Zeit. Anorg. Chem. 96, 103 (1916). APPARATUS. Thermostat. A Freas sensitive thermostat was used to maintain a constant temperature for the entire work of hydra- tion and hydrogen ion concentration measurement. By it a constant temperature of 45 C. .005 was secured. Potentiometer. Measurements for the determination of the concentration of hydrogen ion were made with a Leeds and Northrup direct reading potentiometer of low resistance. Galvanometer. In connection with the potentiometer, a Leeds and Northrup type R, D'Arsonval galvanometer equip- ped with a telescope and scale was employed. Its resistance was 550 ohms, its sensibility 2000 megohms (5 X 10~ 10 amp. per mm. at one meter). The period was six seconds, and the critical damping resistance 11,500 ohms. Standard Cell. A model 4 No. 3921 Weston standard cell served as a basis for all electrical measurements. Its value was 1.01889 volts. This voltage was checked against a cell whose value was checked against a Bureau of Standards standard. Calomel and Hydrogen Cells and Electrodes. The calo- mel and hydrogen cells and electrodes employed in the meas- urement of hydrogen ion concentration were of the type de- scribed in the article of Fales and Vosburg 1 , excepting a modi- fication of the hydrogen cell by a stopcock on the arm leading to the salt bridge. Crucible Furnace. All the sodium monometaphosphate was prepared in an electric resistance furnace. It was cali- brated for temperature by a thermocouple in such a way that its temperature could be controlled by measurement of the current. . A. C. S. 40, 1291 (1918). 10 PREPARATION OF MATERIALS. MONO-SODIUM PHOSPHATE NaH 2 PO 4 2H 2 O A quantity of the purest mono-sodium phosphate obtain- able was recrystallized three times from distilled water. The precipitation was accomplished each time by adding to the aqueous solution an equal volume of redistilled 95% alcohol and cooling in ice water. The solution was constantly stirred till the precipitation was complete. In this way a very uniform crystalline product was obtained. Upon the addition of the alcohol two liquid phases were formed. As the solid phase ap- peared the upper liquid phase gradually disappeared till there was but one liquid and one solid phase at complete precipita- tion. Crystals appeared first at the juncture of the two liquid phases. Attempts to dry the hydrate both by placing it in a desiccator over fused calcium chloride and in an oven at 40 C. proved fruitless. Subsequent analyses for water of hydration from crystals dried in this way gave widely varying results. Hence the drying had to be accomplished in another manner. The crystals already wet with water and alcohol were washed three times with redistilled alcohol on a Buchner fun- nel with suction. Then the washing was continued three times with redistilled anhydrous ether. The filter was changed after each ether washing to avoid the retention of water and alcohol by the filter paper. The hydrate was then spread out upon a clean surface and stirred to allow the ether to evaporate. A day for the final drying was selected when the humidity was low. Otherwise the ^evaporation of the ether would cause a condensation of the moisture in the air upon the surface of the crystals. About fifteen minutes at 20 to 25 C. completed the drying. The hydrate was then kept in a tightly stoppered bottle. Analyses were made on two different lots, one prepared and analysed in March, the other in September with results as follows : Water of hydration plus Lot Sample water of constitution 1 1 34.47% 1 2 34.52% 2 1 34.73% The theoretical for the hydrate NaH 2 PO 4 -2H 2 is 34.63%. The above figures were obtained by transforming the orthophos- phate to the meta according to the method outlined below for the preparation of sodium monometaphosphate. SODIUM MONOMETAPHOSPHATE NaPO 3 . Sodium monometaphosphate was prepared by dehydrating the NaH 2 PO 4 -2H 2 O as above prepared in the electric furnace formerly described in the following manner: The hydrate in a large platinum crucible was held at a temperature of 200 C. for an hour. The temperature was then slowly raised during the next hour till the mass melted to a clear liquid. It was held at this temperature approximately 600 C. for ten minutes. The rheostat was set finally so that a temperature of 450 C. was maintained for the next two hours while the substance crystallized. At the end of this crystallization the metaphos- phate was quickly cooled by dipping the bottom of the crucible in cold water. About thirty-five grams could be prepared at one time in this way. The sodium metaphosphate above prepared was investi- gated by the freezing point method with the following results : Sodium meta- Water in Freezing Molecular phosphate in grams grams point depression weight 5.0472 100 .916 102.5 2.8159 100 .546 95.9 1.3435 100 .351 86.9 These depressions indicate a sodium metaphosphate whose molecular weight corresponds to the formula NaPo 3 (Theoreti- cal 102.04). The above sodium monometaphosphate was for- merly prepared in a somewhat similar way 1 from sodium am- monium hydrogen phosphate by heating the resulting vitrious mass from fusion till it crystallized or by slow cooling from fusion. By taking 2.77 grams of their crystals in 100 c. c. of water, Holt and Meyers obtain a depression of .51 which cor- responds to a molecular weight of 102 and a formula of NaPO 3 . 1 Tantatar, J. Russ. Phys. Chem. Soc., 30, 99 ; Holt and Meyers, J. C. S. Trans. 103, 535. 12 An optical study of the sodium monometaphosphate made by Mr. R. J. Colony of the Department of Geology of Columbia University confirms our belief that the sodium monometaphos- phate prepared above is a distinct chemical individual. Through the kindness of Mr. Colony we are permitted to publish the fol- lowing optical properties : It has an index of refraction, Ng= 1.486 .005, -Np = 1.473 .005, birefringence Ng Np .013 .005. It is apparently monoclinic, optically negative and biaxial with a large optical angle. It shows uniformity in behavior, form, and composition. Sodium monometaphosphate is very soluble in water. It reacts acid to litmus, a three-tenths molar aqueous solution gives a hydrogen ion concentration of 6.5 x 10~ 7 moles per liter. From a three-tenth molar solution white flocculent precipitates which change to crystalline form on standing, may be obtained from solutions of the nitrates of silver, lead, mercury, and bis- muth. With solutions of the nitrates of zinc, cadmium, cobalt, nickel, and copper, white amorphous precipitates are formed. It does not give a precipitate in a solution containing mag- nesium chloride, ammonius chloride, and ammonium hydroxide in moderately high concentrations, the property employed in the separation of monometaphosphoric acid from orthophos- phoric acid. HYDROCHLORIC ACID. The hydrochloric acid used was prepared by distilling a constant boiling solution through a quartz condenser. The first and last portions were rejected. POTASSIUM CHLORIDE. The calomel cells and salt bridges; -were prepared from potassium chloride which was purified by recrystallization three times from distilled water and fusion in platinum. MERCUROUS CHLORIDE. The mercurous chloride employed to make calomel cells for hydrogen ion measurement was prepared by the electrolytic method of Ellis 1 from mercury redistilled according to Hulett and hydrochloric acid prepared as described above. . A. C. S. 38,737 (1916). 13 MAGNESIA MIXTURE. The magnesia mixture used was prepared by dissolving 137.5 grams of magnesium chloride, 225 grams of ammonium chloride, and 250 c. c. ammonium hydroxide (specific gravity .9) in 2250 c. c. of water. METHOD OF PROCEDURE. In planning a method of procedure the factors influencing the reaction have as far as possible been either measured or controlled. The temperature, the concentration of sodium monometaphosphate, the concentration of orthophosphate, the formation of pyrophosphate, and the concentration of hydro- gen ion are the variable factors which influence the hydration of sodium monometaphosphate. The temperature was regulated and controlled at 45 C. .005. The metaphosphoric acid was separated from the ortho and the amount of the latter determined directly. By differ- ence the unchanged meta was obtained. No satisfactory quan- titative method has as yet been found whereby pyrophosphoric acid may be determined in mixtures such as occur in this inves- tigation. So, by other means, an estimate of the amount formed is all that is possible. The concentration of hydrogen ion was measured at intervals during the hydration. PREPARATION OF SOLUTIONS. All solutions made up for hydration were prepared at 20 C. The carefully dried and finely pulverized sodium mono- metaphosphate was weighed and introduced into a volumetric flask. Distilled water was added and the salt completely dis- solved. One-half hour was usually required for complete solu- tion at room temperature. The volume was increased till suffi- cient room was left for the introduction of the required amount of hydrochloric acid used to furnish the hydrogen ion concen- tration in the particular solution. The acid was the constant boiling mixture previously described whose value had been determined by measuring out 30 c. c. portions by means of a burette and building them up to 1000 c. c. The final acid solu- tions were titrated with a standard sodium hydroxide solution whose value was gotten by using Bureau of Standards benzoic acid. Phenolphthalein was used as an indicator. As the acid was added the flask was rotated so as to keep from acquiring as little as possible a higher concentration of hydrogen ion in 15 any portion of the solution than that ultimately desired. After the introduction of the acid the solution was quickly cooled to 20 C. and the flask rilled up to the graduation. After thorough mixing, the solution was put in a "non-sol" bottle and placed in the bath. The whole operation, beginning with the addition ot the acid, required not more than ten minutes. The specific gravity of the solution was taken at 20 C. by means of a Westphal balance at the beginning of the reaction. No change of volume was observed during the hydration great- er than one part in one thousand, the precision of the bal- ance 1 . Hence one specific gravity measurement for each solu- tion served as a basis for calculation of the percentage of meta- phosphoric acid transformed to the ortho. The concentrations of the solutions were all calculated in moles per liter. There- fore, knowing the specific gravity and the concentration in moles per liter, the amount of sodium monometaphosphate in any weighed quantity of solution could be determined. THE SEPARATION OF MONOMETAPHOSPHORIC ACID FROM ORTHOPHOSPHORIC ACID. Monometaphosphoric acid was separated from orthophos- phoric acid by means of magnesia mixture in a cold solution. As previously stated, a solution of sodium monometaphosphate does not give a precipitate with magnesia mixture in concen- trations used in this procedure and in fact very much higher concentrations. This method of separation has been tested both qualitatively and quantitatively (see Table 1). Seven-tenths of a gram of sodium monometaphosphate together with 25 c. c. of the magnesia mixture prepared above in a total volume of 125 c. c. was allowed to stand twenty-four hours repeatedly and no precipitate appeared while a precipitate of the orthophos- phate appeared immediately in another solution similarly treated, excepting that one milligram of phosphorus in the form of orthophosphate was added. It remains now to be shown that monometaphosphoric acid is quantitatively separ- able from the ortho and that no appreciable hydration occurs during the time of standing required for the precipitation of 1 Montemartini and Egid, Gazz. Ital. Chim. 31, I, 394 (1901). 16 12 C PL, W) O 6^ PH^ GO eo ., ig^ e PH * fr- ia W^2 i-H CO CVJ QN ON ON fO PO CO co ro co 00 ON ig re PO ro ro <^ fO ON ON ON Srx O . ^ ^ 10 10 10 ro fO CO ro ro CO ON ON ON CO ro CO ro I-H rh I-H CM 10 O^T-H ro fO ro ro ro ro ON ON ON 17 the magnesium ammonium phosphate. By referring to Table 1 it may be noted that thirty determinations of orthophosphate, according to the method outlined below, in the presence of varying quantities of sodium monometaphosphate from 900 milligrams to 100 milligrams have been made. The amount of orthophosphate used has varied and the time of standing has been 6, 12, and 18 hours respectively. There is an increase in amount found over the amount added which is of the same order irrespective of the time of standing, whether it was 6, 12, or 18 hours. This shows that hydration is not the cause of the increase; for if it were, the amount of increase would be a direct function of the time. The increase seems to be due to absorption of the sodium monometaphosphate by the mag- nesium ammonium phosphate precipitate, which is subsequent- ly hydrated during the dissolving of the magnesium ammonium phosphate with hot hydrochloric acid. The reaction as will be shown is rapid in a hot acid solution. The analyses were run in series of five each and the time of standing in the hot acid solution was about the same for all except the one starred in Table 1. This one was re-precipitated immediately and the value of it is smaller than that obtained for both the one that stood six and the one that stood 18 hours in the presence of the same amount of sodium monometaphos- phate. At any rate the maximum deviation from the amount used is not greater than .82 of a milligram of phosphorus or 1.5%. From the experimental data below it will be observed that almost all the determinations were made in the presence of much less than 300 milligrams of sodium monometaphos- phate where the maximum deviation is in the region of .5 milli- gram or one per cent. DETERMINATION OF ORTHOPHOSPHATE, Orthophosphate was determined by the standard gravi- metric method. The samples of the solution were taken by means of Bailey weighing burettes. A standard final volume of 125 c. c. including 25 c. c. of magnesia mixture was used in all determinations. Before precipitation each sample was di- luted to 100 c. c. The separation of the magnesium ammonium 18 phosphate precipitate from the unprecipitated meta was made by filtration not longer than sixteen hours nor less than six hours after the first precipitation. After separation and wash- ing with an ammonium hydroxide-ammonium nitrate solution, the orthophosphate precipitate was dissolved with hot hydro- chloric acid, re-precipitated by adding to the solution diluted to 100 c. c. a concentrated ammonium hydroxide solution (sp. gr. .9), 10 c. c. in excess of that required for neutralization. Finally after twelve hours standing the magnesium ammonium phosphate was filtered through a weighed gooch crucible, wash- ed, and ignited and weighed as magnesium pyrophosphate. By this method the amount of the monometaphosphate trans- formed to ortho could be determined. FORMATION OF PYROPHOSPHATE. The analytical results vary somewhat due to the forma- tion of pyrophosphate in the reaction. With no method at pres- ent for the separation of pyrophosphoric acid from the ortho except the prevention of its precipitation by an excess of mag- nesia mixture (magnesium pyrophosphate is soluble in an ex- cess of magnesium salts) at times the ortho precipitate was con- taminated a little with it. That there was pyrophosphoric acid formed there was no doubt. The magnesium ammonium phos- phate is a definite crystalline product very readily filtered. When pyrophosphate is present these crystals are mixed with a white gelatinous precipitate which is soluble in an excess of magnesium salts. The formation of pyrophosphate was later confirmed by hydrogen ion measurements. MEASUREMENT OF CONCENTRATION OF HYDROGEN ION. All hydrogen ion measurements were made at 45 C. by The Saturated Potassium Chloride 'Calomel Cell method de- veloped in this department 1 . Samples of the solution in process of hydration were taken by means of a pipette and introduced into the hydrogen cell previously steamed and rinsed three times with the solution being measured. After fifteen minutes 1 Kales -and Mudge, J. A. C. S. 42, 2434 (1920). 19 the time required for the system to reach equilibrium, the meas- urement was made. The hydrogen used was purified by pass- ing it successively through acid permanganate, alkaline pyro- gallol, and a portion of the same solution to be measured placed in the thermostat. The calculations for the molar concentration of hydrogen ion were made by means of the formula, A E derived from the Nernst formula. In this formula C is the concentration of the hydrogen ion in moles per liter, T the absolute temperature, B a constant whose value is .000198 obtained in the transformation of R in RT C the formula used, E = - In - to volt-coulombs and nF C, subsequently dividing by 96,494 coulombs multiplied by the equivalence of hydrogen and the logarithmic modulus .4343 thus fixing its dimensions as volts ; E, the observed voltage, and A a constant determined experimentally by measurement of a .0989 M. hydrochloric acid solution whose value was prev- iously checked against Bureau of Standards Benzoic acid. By employing the precentage 91.3%, for a .1 M hydrochloric acid solution determined from the data and curves in the Carnegie Publications for 1907 by Noyes and others, pages 141 and 339, a value of .2356 is obtained whose dimensions are also volts the theoretical voltage of a one molar hydrogen ion solution for the combination used in this research. The difference in ionization between a .0989 M. and a .1 M. hydrochloric acid solution is less than the experimental error. The formula for 45 C. becomes .2356 E .2356 E log C H < - - .000198 (45 + 273) .063 20 EXPERIMENTAL DATA. The following table outlines the plan adopted in securing experimental data on hydration of solutions of different hy- drogen ion and monometaphosphate concentrations. TABLE 2. Solutions studied. Solution Cone. NaPO 3 moles per liter at 20 C. Cone. HC1 moles per liter at 20 C. Specific gravity at 20 C. c .5 .483 1.045 D .5 .483 1.044 G .5 .339 1.041 E .5 .339 1.042 B .5 .192 1.042 H .5 .192 1.041 K .3 .339 1.025 M .3 .339 1.026 N .1 .339 1.011 O .1 .339 1.011 Z .3 .010 1.025 ZA .3 .010 1.025 s .3 .000 1.025 SA .3 .000 1.025 From the outline it will be observed that hydrations were run in duplicate with the exception of the last four. Duplicate samples of the latter were taken as shown by tables which follow. The hydration and hydrogen ion concentration tables of solutions C, G, B, M, and N which are duplicates of D, E, H, K, and O respectively have been omitted. The mean deviation of the results in duplicates is not greater than five per cent when the concentration of pyrophosphate is high at the begin- ning nor greater than one per cent, when the hydration nears completion. 21 TABLE 3. Hydration in Solution D. Concentration NaPO 3 = 5 M. at 20 C. Temperature = 45 C. Concentration HC1 = .483 M. at 20 C. Specific Gravity = 1.044 at 20 C. No. of Time Total Phos- Phosphorus as Percentage sample hrs. min. phorus in rugs. ortho in nigs. hydrated 1 1:45 89.61 7.41 8.27 2 4:40 79.14 37.32 47.13 3 10:40 78.30 51.71 65.99 4 24:10 79.37 64.81 81.59 5 48:25 78.60 69.15 87.93 6 72:55 79.84 74.20 92.66 7 120:10 78.89 76.37 96.74 8 168:42 74.42 73.31 98.44 9 252:10 78.15 79.16 101.20 This table furnishes the data for the curve in figure 1. TABLE 4. Hydrogen Ion Concentration during Hydration in Solution D. No. of sample 1 2 3 4 5 6 7 8 9 10 Time hrs. min. 1:00 5:15 11:30 25:15 49:00 74:25 121 :25 170:00 243:00 152:00 Voltage .2667 .2793 .2838 .2874 .2924 .2957 .2977 .3022 .2995 .2995 Concentration in moles per liter .3209 .2024 .1717 .1506 .1255 .1112 .1033 .0877 .0968 .0968 This table furnishes the data for the curve in figure 1. 22 TABLE 5. Hydration in Solution E. Concentration of NaPO 3 = .5 M. at 20 C. Temperature = 45 C. Concentration of HC1 = .339 M. at 20 C. Sp. Gr. = 1.042 at 20 C. No. of Time Total Phos- Phosphorus as Percentage sample hrs. min. phorus in mgs. ortho in mgs. hydrated 1 2:10 151.09 11.43 7.56 2 5:10 77.36 19.96 25.80 3 11:10 77.42 38.91 50.26 4 23:10 76.37 51.48 67.41 5 48:35 78.02 58.59 75.10 6 71:25 80.03 65.95 80.53 7 119:03 78.42 66.09 84.28 8 166:59 72.98 66.45 91.05 9 239:25 77.14 73.84 95.72 10 383 :25 86.54 87.16 102.80 This table furnishes the data for the curve in figure 1. TABLE 6. Hydrogen Ion Concentration during Hydration in Solution E. No. of sample 1 2 3 4 5 6 7 8 9 10 Time hrs. min. 1:35 5:45 10:55 24:10 47:20 72:55 120:10 167:45 240:40 384:25 Voltage .2823 .2950 .3004 .3082 .3138 .3174 .3216 .3242 .3276 .3276 Concentration in moles per liter .1815 .1140 .0936 .0704 .0574 .0503 .0434 .0392 .0347 .0347 This table furnishes the data for the curve in figure 1. 23 TABLE 7. Hydration in Solution H. Concentration of NaPO 3 = .5 M. at 20 C. Temperature = 45 C. Concentration of HC1 = .192 M. at 20 C. Sp. Gr. = 1.041 at 20 C. No. of sample 1 2 3 4 5 6 7 8 11 12 13 14 15 16 17 18 Time Total Phos- hrs. min. phorus in mgs. 6:12 157.33 Phosphorus as Percentage ortho in mgs. hydrated 21.74 13.82 13:22 78.80 23.22 29.47 23:29 77.28 34.70 44.91 35:57 47:17 84.62 83.33 Sample lost in 52.82 filtration 63.38 71:12 81.57 56.42 69.16 119:19 59.59 59.59 73.40 167:36 75.55 60.88 80.58 192:32 77.12 60.23 78.11 215:18 79.55 65.42 82.42 263 :42 78.28 66.65 85.13 335 :42 79.63 68.29 85.76 457:07 85.64 79.08 92.34 678:36 79.46 76.29 96.01 875:18 67.23 66.17 98.43 875:18 94.86 93.29 98.36 This table furnishes the data for the curve in figure 1. TABLE 8. Hydrogen Ion Concentration during Hydration in Solution H. No. of sample 1 2 3 4 5 6 7 8 Time hrs. min. 1:17 5:55 13:30 24:30 36:30 48:15 71:57 120:25 Voltage .2960 .3147 .3220 33.13 .3361 .3386 .3424 .3487 Concentration in moles per liter .1101 .0555 .0425 .0303 .0254 .0231 .0202 .0160 24 9 10 11 12 13 14 15 16 TABLE 8 Continued. 168:17 .3522 193 :25 .3533 216:04 .3539 264:34 .3563 337 :00 .3580 457:48 .3590 673:10 .3614 876:12 .3630 .0141 .0135 .0133 .0121 .0114 .0110 .0100 .0095 This table furnishes the data for the curve in figure 1. TABLE 9. Hydration in Solution K. Concentration of NaPO 3 = .3 M. at 20 C. Temperature = 45 C. Concentration of HC1 = .339 M. at 20 C. Sp. Gr. = 1.025 at 20 C. No. of sample 1 2 3 4 5 6 7 8 9 10 Time hrs. min. 1:30 Total Phos- phorus in mgs. 190.96 Phosphorus as ortho in mgs. 17.64 Percentage hydrated 9.24 3:00 146.91 53.08 36.05 7:00 97.77 57.50 58.82 15:00 61.37 40.00 65.17 27:00 79.75 58.65 73.54 51:00 72.86 62.83 86.22 83:25 93.01 87.33 93.89 120:10 50.88 49.00 96.31 168:25 49.18 47.91 97.44 240:01 46.05 45.41 98.60 This data furnishes the data for the curve in figure 2. TABLE 10. Hydrogen Ion Concentration during Hydration in Solution K. No. of sample 1 2 3 Time hrs. min. 1:10 3:10 7:55 Voltage .2781 .2808 .2858 Concentration in moles per liter .2115 .1917 .1597 25 TABLE 1O Continued 4 5 6 7 8 9 10 11 12 13 14 14:50 24:31 50:05 83:55 120:44 169:00 194:26 242:00 250:53 335 :07 365 :45 .2884 .2929 .2953 .2969 .3012 .2997 .2992 .2992 .3018 .3006 .3007 .1452 .1232 .1128 .1064 .0909 .0961 .0978 .0978 .0900 .0930 .0926 This data furnishes the data for the curve in figure 2. TABLE 11. Hydration in Solution O. Concentration of NaPO 3 = .1 M. at 20 C. Temperature = 45 C. Concentration of HC1 = .339 M. at 20 C. Sp.Gr.= 1.011 M. at 20 C. No. of sample Time Total Phos- hrs. min. phorus in mgs. Phosphorus as ortho in mgs. Percentage hydrated 1 1:30 97.86 11.33 11.83 2 3:00 61.70 25.95 42.06 3 7:10 64.07 44.26 69.08 4 13:10 63.53 50.26 79.10 5 24:10 70.02 61.85 88.34 6 47:40 61.67 59.34 96.22 7 72:10 62.90 61.63 97.89 This table furnishes the data for the curve in figure 3. 26 TABLE 12. Hydrogen Ion Concentration during the Hydration in Solution O. No. of sample 1 2 3 4 5 6 7 Time hrs. min. 1:00 3:45 7:15 13:40 24:50 49:00 72:53 Voltage .2715 .2714 .2734 .2732 .2751 .2764 .2760 Concentration in moles per liter .2702 .2702 .2522 .2530 .2361 .2251 .2284 This table furnishes the data for the curve in figure 3. TABLE 13. Hydration in Solution Z and Z A. Concentration of NaPO 3 = .3 M. at 20 C. Temperature = 45 C. Concentration of HC1 = .01 M. at 20 C. Sp. Gr. = 1.022 at 20 C. No. of Time Total Phos- Phosphorus as Percentage sample hrs. min. phorus in mgs. ortho in mgs. hydrated 1-Z-A 166:15 190.36 23.41 12.30 2-Z-A 166:15 196.32 23.58 12.01 3-Z-A 333:00 165.99 42.51 25.34 4-Z-A 333:00 191.81 .... .... 5-Z-A 501:00 148.31 64.64 43.60 6-Z-A 501:00 139.51 56.14 40.30 7-Z 665:00 92.31 44.88 48.61 8-Z 665:00 98.34 47.61 48.41 9-Z 952:30 87.05 51.15 58.75 10-Z 952 :30 99.95 57.53 57.57 11-Z 1386:45 89.21 65.14 73.02 12-Z 1386:45 101.11 73.61 72.81 13-Z 2248:30 94.% 82.65 87.03 14-Z 2248:30 103.65 88.72 87.58 15-Z 2944:45 75.06 70.07 93.35 16-Z 2944:45 66.49 61.93 93.15 17-Z 3469:20 79.87 77.43 96.95 18-Z 3469:20 72.21 70.73 97.14 This table furnishes the data for the curve in figure 4. 27 TABLE 14. Hydrogen Ion Concentration during the Hydration in Z. No. of Time Concentration in sample hrs. min. Voltage moles per liter 1 0:40 .3637 .009477 2 7:45 .3777 .005552 3 19:45 .3829 .004591 4 44:00 .3896 .003594 5 72:20 .3960 .002844 6 120:20 .4039 .002131 7 167:41 .4089 .001841 8 480:03 .4258 .000957 9 953:38 .4393 .000584 10 1553:45 .4455 .000466 11 2946:03 .4507 .000384 12 3570:47 .4524 .000362 This table furnishes the data for the curve in figure 4. TABLE 15. Hydration in Solution S and S-A. Concentration NaPO 3 = .3 M. at 20 C. Temperature = 45 C. Concentration HC1 = 0. Sp. Gr. = 1.022 at 20 C. No. of sample 1-S-A Time days 25 Total Phos- phorus in mgs. 621.02 Phosphorus as ortho in mgs. 11.21 Percentage hydrated 1.81 2-S-A 25 593.65 10.62 1.79 3-S-A 45 448.48 23.80 5.31 4-S-A 45 443.94 22.09 5.00 5-S 60 232.07 17.31 7.46 6-S 60 240.47 18.20 7.56 7-S 74 132.17 13.77 10.42 8-S 74 152.78 15.89 10.40 9-S 88 115.72 15.22 13.15 10-S 88 118.56 15.80 13.33 11-S 109 99.44 19.54 19.65 12-S 109 90.76 17.67 19.47 28 TABLE 15 Continued. 13-S 149 91.92 29.80 32.42 14-S 149 99.52 32.00 32.23 15-S 177 98.02 40.56 41.37 16-S 177 98.13 40.67 41.44 17-S 200 99.83 47.91 49.11 18-S 200 99.21 48.28 49.16 This table furnishes the data for the curve in figure 5. TABLE 16. Hydrogen Ion Concentration during Hydration in Solution S. No. of Time Concentration x 10 6 sample 1 hrs. min. 1:30 Voltage .6252 in moles per liter .65 2 4:30 .6234 .70 3 10:48 .6195 .81 4 23:00 .6070 1.27 5 48:30 .5900 2.37 6 72:00 .5798 3.44 7 96:00 .5636 6.22 8 199:15 .5679 5.31 9 216:50 .5641 6.11 10 289:43 .5565 8.06 11 343 :37 .5555 8.36 12 480:36 .5449 12.30 13 602:45 .5406 14.52 14 724:45 .5373 16.68 15 890:45 .5339 18.41 16 1158:40 .5284 22.51 17 1494:33 .5248 25.68 18 2183 :50 .5209 29.61 19 4799 :28 .5109 41.80 This table furnishes the data for the curve in figure 5. 29 TABLE 17. The Concentration of Hydrogen Ion in Monosodiumphosphate Hydrochloric Acid Solutions. (The solutions were made up at 20 C. and measured at 45 C.) Concentration HC1 Moles per liter at 20 C. .1 .2 Con.