Compilation - Ammonium dihydrogenphosphate with Diammonium hydrogenphosphate, Potassium thiosulfate and Water (IUPAC SDS Volume 66)
SDS Volume (3006)
Volume 66. Ammonium Phosphates, p None
Original Measurements
Babenko, A. M.; Andrianov, A. M.; Zh. Neorg. Khim. 1984, 29, 2663.
Variables:
K2S2O3 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. The material designated "mixture" was prepared by mixing equimolar amounts of $\ce{NH4H2PO4}$ and $\ce{(NH4)2HPO4}$ and homogenizing by grinding in a mortar. Potassium thiosulfate (p., TU 6-09-44-70) was recrystallized twice and dried at 105°C.
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 thiosulfate, $\ce{ K2S2O3 }$; [10294-66-3] 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-K2S2O3-H2O system.
| $T$ (°C) | 100w1 | 100w2 | 100w3 | w4 | 100w5 | m2 (mol/kg) | m3 (mol/kg) | m4 (mol/kg) | Phase (s) () |
|---|---|---|---|---|---|---|---|---|---|
| -21.5 | 0 | 0 | 0 | 52.0 | 48.0 | 0 | 0 | 5.69 | A + B |
| -21.6 | 5.0 | 2.3 | 2.7 | 50.0 | 45.0 | 0.45 | 0.45 | 5.84 | A + B |
| -22.5 | 11.2 | 5.2 | 6.0 | 44.0 | 44.8 | 1.04 | 1.0 | 5.16 | A + C |
| -27.5 | 16.0 | 7.4 | 8.6 | 33.6 | 50.4 | 1.3 | 1.3 | 3.50 | A + C |
| -21.6 | 19.2 | 8.9 | 10.3 | 36.0 | 44.8 | 1.7 | 1.73 | 4.22 | A + C |
| -15.4 | 24.0 | 11.2 | 12.8 | 22.8 | 53.2 | 1.83 | 1.83 | 2.25 | A + C |
| -23.0 | 8.0 | 3.7 | 4.3 | 45.0 | 47.0 | 0.69 | 0.69 | 5.03 | A + B + C |
| -17.0 | 27.3 | 12.7 | 14.6 | 22.0 | 50.7 | 2.18 | 2.18 | 2.28 | A + C + D |
| -8.6 | 38.6 | 22.2 | 26.4 | 0 | 61.4 | 3.14 | 3.14 | 0 | A + D |
| -13.0 | 36.0 | 16.8 | 19.2 | 6.4 | 57.6 | 2.53 | 2.53 | 0.58 | A + D |
| -14.2 | 32.0 | 14.9 | 17.1 | 13.6 | 54.4 | 2.38 | 2.38 | 1.31 | A + D |
| 39.0 | 61.0 | 28.4 | 32.6 | 0 | 39.0 | 6.33 | 6.33 | 0 | C + D |
| 19.0 | 47.0 | 21.9 | 25.1 | 6.0 | 47.0 | 4.05 | 4.05 | 0.67 | C + D |
| 10.0 | 36.12 | 16.82 | 19.30 | 14.0 | 49.88 | 2.931 | 2.931 | 1.47 | C + D |
| 10.0 | 42.55 | 19.81 | 22.74 | 7.5 | 49.95 | 3.447 | 3.447 | 0.79 | C + D |
| -1.0 | 6.6 | 3.1 | 3.5 | 51.37 | 42.03 | 0.64 | 0.64 | 6.422 | B + C |
| 12.0 | 5.0 | 2.3 | 2.7 | 57.0 | 38.0 | 0.53 | 0.53 | 7.88 | B + C |
(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 = K2S2O3; C = NH4H2PO4; D = (NH4)2HPO4.
(a) "Mixture" is an equimolar mixture of NH4H2PO4 and (NH4)2HPO4.
(b) These molalities were calculated by the compiler. The units are: mol kg-1
(c) The solid phases are: A = ice; B = K2S2O3; C = NH4H2PO4; D = (NH4)2HPO4.
