Compilation - Ammonium dihydrogenphosphate with Diammonium hydrogenphosphate, Potassium sulfate and Water (IUPAC SDS Volume 66)
SDS Volume (3005)
Volume 66. Ammonium Phosphates, p None
Original Measurements
Babenko, A. M.; Andrianov, A. M.; Zh. Neorg. Khim. 1984, 29, 2663.
Variables:
K2SO4 in a mixture containing a mole ratio of NH4H2PO4/(NH4)2HPO4 = 1.
Prepared by:
Method/Apparatus/Procedure:
An improved visual polythermic method [1] was used.
Source and Purity of Materials:
- Chemically pure or reagent grade salts were recrystallized twice and dried at 30°C to 40°C. The material designated "mixture" was prepared by mixing equimolar amounts of $\ce{NH4H2PO4}$ and $\ce{(NH4)2HPO4}$ and homogenizing by grinding in a mortar.
Estimated Errors:
Ambient temperature: Precision of temperature measurement was ±0.4 K.
References
1 Erayzer, L. N.; Kaganskiy, I. M.; Zavod. Lab. 1967, 1, 119.
Components:
- Ammonium dihydrogenphosphate, $\ce{ NH4H2PO4 }$; [7722-76-1] NIST WebBook
- Diammonium hydrogenphosphate, $\ce{ (NH4)2HPO4 }$; [7783-28-0] NIST WebBook
- Potassium sulfate, $\ce{ K2SO4 }$; [7778-80-5] NIST WebBook
- Water, $\ce{ H2O }$; [7732-18-5] NIST WebBook
Experimental Data
Part 1. Points of simultaneous crystallization of two or three solid phases in the NH4H2PO4-(NH4)2HPO4-K2SO4-H2O system.
| $T$ (°C) | w1 | w2 | w3 | 100w4 | 100w5 | m2 (mol/kg) | m3 (mol/kg) | m4 (mol/kg) | Phase (s) () |
|---|---|---|---|---|---|---|---|---|---|
| -1.6 | 0 | 0 | 0 | 6.5 | 93.5 | 0 | 0 | 0.40 | A + B |
| -4.0 | 9.0 | 4.2 | 4.8 | 10.0 | 81.0 | 0.45 | 0.45 | 0.71 | A + B |
| -6.0 | 18.06 | 8.41 | 9.65 | 9.7 | 72.24 | 1.01 | 1.01 | 0.77 | A + B |
| -9.0 | 27.3 | 12.7 | 14.6 | 9.0 | 63.7 | 1.73 | 1.73 | 0.81 | A + B |
| -10.3 | 32.2 | 15.0 | 17.2 | 8.0 | 59.8 | 2.18 | 2.18 | 0.77 | A + B |
| 11.0 | 41.85 | 19.48 | 22.37 | 7.0 | 51.15 | 3.311 | 3.311 | 0.79 | B + C |
| 18.0 | 46.5 | 21.6 | 24.9 | 7.0 | 46.5 | 4.05 | 4.05 | 0.86 | B + C |
| -8.6 | 38.6 | 18.0 | 20.6 | 0 | 61.4 | 2.54 | 2.54 | 0 | A + C |
| -9.1 | 36.0 | 16.8 | 19.2 | 3.2 | 60.8 | 2.40 | 2.40 | 0.30 | A + B + C |
| 39.0 | 61.0 | 28.4 | 32.6 | 0 | 39.0 | 6.33 | 6.33 | 0 | C + D |
| 45.0 | 62.2 | 29.0 | 33.2 | 2.8 | 35.0 | 7.19 | 7.19 | 0.46 | C + D |
(a) "Mixture" is an equimolar mixture of NH4H2PO4 and (NH4)2HPO4.
(b) The molalities were calculated by the compiler. The units are: mol kg-1.
(c) The solid phases are: A = ice; B = K2SO4; C = NH4H2PO4; D = (NH4)2HPO4.
(a) "Mixture" is an equimolar mixture of NH4H2PO4 and (NH4)2HPO4.
(b) These values were calculated by the compiler. The units are: mol kg-1
(c) The solid phases are: A = ice; B = K2SO4; C = NH4H2PO4; D = (NH4)2HPO4.
