SDS Volume (2949)
Volume 66. Ammonium Phosphates, p None
Original Measurements
Brosheer, J. C.; Anderson Jr., J. F.; J. Am. Chem. Soc. 1946, 68, 902.
Variables:
Room Temp: Composition at 60 and 75 °C
Prepared by:
Method/Apparatus/Procedure:
Mixtures were placed in 300 mL glass-stoppered bottles which were rotated end-over-end in a constant temperature bath for at least three days. Mixtures in which the vapor pressure of $\ce{NH3}$ prevented accurate sampling from open flasks were placed in special flasks for use under pressure. Aliquots of $\ce{HCl}$ solutions of the samples were analyzed for $\ce{NH3}$ by addition of alkali and distillation into standard acid. Other aliquots were analyzed for $\ce{H3PO4}$ by double precipitation as $\ce{NH4MgPO4.6H2O}$ and ignition to $\ce{Mg2P2O7}$.
Source and Purity of Materials:
- Reagent grade $\ce{H3PO4}$, monoammonium phosphate, diammonium phosphate and aqueous ammonia were used. Recrystallization did not alter the solubility of the salts.
Estimated Errors:
Ambient temperature: The temperature was kept constant to within ±0.05 K. Duplicate results were accepted only when they agreed within 0.5%.
Components:
- Ammonia, $\ce{ NH3 }$; [7664-41-7] NIST WebBook
- Phosphoric acid, $\ce{ H3PO4 }$; [7664-38-2] NIST WebBook
- Water, $\ce{ H2O }$; [7732-18-5] NIST WebBook
Experimental Data
Table II. Solubility in the NH3-H3PO4-H2O system at 75°C. The solid phase was determined by the Schreinemakers' method.
| 100w1 | 100w2 | 100w3 | m1 (mol/kg) | m2 (mol/kg) | Phase (s) () |
|---|---|---|---|---|---|
| 6.85 | 80.35 | 12.80 | 31.42 | 64.05 | A |
| 6.72 | 75.24 | 18.04 | 21.87 | 42.56 | A |
| 13.55 | 37.46 | 48.99 | 16.24 | 7.80 | B + C |
| 12.88 | 35.61 | 51.51 | 14.68 | 7.05 | C |
| 12.47 | 33.02 | 54.51 | 13.43 | 6.18 | C |
| 12.08 | 29.57 | 58.35 | 12.16 | 5.17 | C |
| 11.91 | 27.16 | 60.93 | 11.48 | 4.55 | C |
| 11.98 | 25.74 | 62.28 | 11.30 | 4.22 | C |
| 11.83 | 22.60 | 65.57 | 10.59 | 3.52 | C |
| 11.94 | 20.86 | 67.20 | 10.43 | 3.17 | C |
| 12.15 | 14.96 | 72.89 | 9.79 | 2.09 | C |
| 13.47 | 8.86 | 77.67 | 10.18 | 1.16 | C |
| 15.40 | 5.36 | 79.24 | 11.41 | 0.690 | C |
| 20.47 | 1.92 | 77.61 | 15.49 | 0.252 | C |
| 23.73 | 1.09 | 75.18 | 18.53 | 0.148 | C |
(a) These values were calculated by the compiler.
(b) The solid phases are: A = NH4H2PO4; B = (NH4)2HPO4.
(c) This is the average of five determinations.
(a) These values were calculated by the compiler.
(b) The solid phases are: A = NH4H2PO4; B = (NH4)2HPO4; C = (NH4)7(PO4) or (NH4)3PO4·2((NH4)2HPO4.
(c) This is the average of four determinations.
