SDS Volume (2950)
Volume 66. Ammonium Phosphates, p None
Original Measurements
Chernova, K. S.; Izv. Sektora Fiz. -Khim. Analiza, Inst. Obshch. Neorg. Khim. Akad. Nauk USSR 1947, 15, 112.
Variables:
Room Temp: Composition at 0 °C in the region where (NH4)2HPO4·2H2O and (NH4)2HPO4 are the solid equilibrium phases. °C
Prepared by:
Method/Apparatus/Procedure:
The isothermal method was used with mechanical stirring and an ice-water mixture as the bath. The equilibrium was ascertained by repeated analyses of the liquid phase (no details are given). Equilibrium was reached within 24 hrs.
Source and Purity of Materials:
- Anhydrous $\ce{(NH4)2HPO4}$ was recrystallized from a solution containing a small excess of ammonia. No other information is given.
Estimated Errors:
Ambient temperature: No information is given.
Mass concentration (m/v) (1): No information is given.
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
Solubility in the crystallization field of (NH4)2HPO4·2H2O in the (NH4)3PO4-H3PO4-H2O system at 0°C.
| 100w1 | 100w2 | 100w3 | m1 (mol/kg) | m2 (mol/kg) | Phase (s) () |
|---|---|---|---|---|---|
| 9.35 | 26.95 | 63.70 | 8.62 | 4.32 | A |
| 7.80 | 22.60 | 69.60 | 6.58 | 3.31 | B |
| 7.38 | 20.79 | 71.83 | 6.03 | 2.95 | B |
| 8.38 | 26.31 | 65.31 | 7.53 | 4.11 | B |
| 8.31 | 26.52 | 65.17 | 7.49 | 4.15 | B |
| 9.25 | 30.40 | 60.35 | 9.00 | 5.14 | B |
| 9.50 | 31.93 | 58.57 | 9.52 | 5.56 | B |
| 32.20 | B | ||||
| 9.85 | 33.30 | 56.85 | 10.17 | 5.98 | B |
| 10.04 | 34.24 | 55.72 | 10.58 | 6.27 | B |
| 10.12 | 35.26 | 54.62 | 10.88 | 6.59 | B |
| 10.71 | 37.84 | 51.45 | 12.22 | 7.50 | A |
| 11.14 | 41.06 | 47.80 | 13.68 | 8.77 | A + C |
(a) These values were calculated by the compiler.
(b) The solid phases are: A = (NH4)2HPO4; B = (NH4)2HPO4·2H2O; C = NH4H2PO4.
(c) The meaning of this point is not clear. The compiler assumes it is a parallel analysis of H3PO4 in the solution above.
