Solubility System: Ammonia with Phosphoric acid, Sulfuric acid and Water
Components:

(1) Ammonia, NH3; [7664-41-7] NIST WebBook
(2) Phosphoric acid, H3PO4; [7664-38-2] NIST WebBook
(3) Sulfuric acid, H2SO4; [7664-93-9] NIST WebBook
(4) Water, H2O; [7732-18-5] NIST WebBook

Original Measurements

Uno, S.; Kogyo Kagaku Zashi 1940, 43, 399-402.
Uno, S.; J. Soc. Chim. Ind., Japan, Suppl. Binding 1940, 43, 168B-170B.

Variables:

Ambient temperature: Composition at 0 °C, 25 °C, 40 °C, 70 °C and 100 °C

Prepared by:

J. Eysseltová, H. Miyamoto

Method/Apparatus/Procedure:

The isothermal method was used. Ammonium sulfate, phosphoric acid and water were placed in ampules. The mixtures were shaken in a thermostat at 25 °C and 70 °C. After equilibrium was established, the mixtures were allowed to settle. A pipet was used to obtain aliquots of the saturated solution for analysis. The saturated solution was evaporated to dryness and the solid obtained was dried at 110 °C to 115 °C to determine total solid content. The NH3 content was determined by the distillation method. The phosphate and sulfate contents were determined gravimetrically as Mg(NH4)PO4 and BaSO4, respectively.

Source and Purity of Materials:
  1. Chemically pure reagents were used. Ammonium sulfate was recrystallized.
Estimated Errors:

Ambient temperature: precision ±0.05 K at 298 K and ±0.5 K at 343 K.
Mass concentration (m/v) (1): nothing specified.

Experimental Values:
Composition of saturated solutions in the (NH4)2SO4-H3PO4-H2O system.
T (°C) 100w1 w2 Phase (s)a
25.0 43.3 0.0 A
25.0 41.0 10.6 A
25.0 39.9 15.6 A
25.0 39.7 19.4 A + B
25.0 39.8 19.4 A + B
25.0 36.5 22.8 B
25.0 33.8 25.1 B
25.0 29.7 31.7 B
25.0 24.0 40.6 B
25.0 18.3 52.3 B
25.0 15.8 58.6 B
25.0 13.3 64.4 B
70.0 47.8 0.0 A
70.0 45.7 9.46 A
70.0 44.6 17.3 A
70.0 44.1 23.9 A
70.0 44.0 27.3 A
70.0 44.2 29.6 A + B
70.0 43.4 30.3 B
70.0 42.2 31.3 B
70.0 38.6 36.3 B
70.0 35.1 41.2 B
70.0 30.6 47.7 B
70.0 28.3 52.0 B
70.0 24.1 59.9 B

(a) The solid phases are: A = (NH4)2SO4; B = (NH4)2H3(PO4)(SO4).

Composition of saturated solutions in the (NH4)2H3(PO4(SO4)-(NH4)2SO4-H2O system.
T (°C) g1/100 g H2O (g1/100 g2) g2/100 g H2O (g1/100 g2) Phase (s)b
0.0 70.6 0.0 A
0.0 60.8 20.1 A
0.0 45.2 51.9 A
0.0 36.1 72.6 A + B
0.0 27.7 80.1 B
0.0 10.9 93.2 B
0.0 0.0 107.9 B
25.0 76.2 0.0 A
25.0 55.1 51.4 A
25.0 37.2 100.3 A
25.0 33.0 111.7 A + B
25.0 33.3 111.4 A + B
25.0 16.1 125.2 B
25.0 0.0 143.4 B
40.0 80.8 0.0 A
40.0 60.6 51.4 A
40.0 43.4 104.6 A
40.0 27.6 150.2 A + B
40.0 27.7 149.3 A + B
40.0 13.4 163.1 B
40.0 0.0 176.0 B
70.0 91.4 0.0 A
70.0 73.5 49.6 A
70.0 55.8 106.4 A
70.0 37.0 175.4 A
70.0 24.9 223.3 A
70.0 16.4 265.8 A + B
70.0 9.44 270.8 B
70.0 0.0 277.5 B
100.0 103.6 0.0 A
100.0 73.2 105.3 A
100.0 43.2 218.1 A
100.0 27.4 296.9 A
100.0 17.6 375.6 A
100.0 13.4 441.0 A
100.0 11.2 481.6 A + B
100.0 12.0 480.2 A + B
100.0 5.27 482.4 B
100.0 0.0 490.0 B

(a) The composition unit is: g/100g H2O. (b) The solid phases are: A = (NH4)2SO4; B = (NH4)2H3(PO4)(SO4).

Composition of saturated solutions in the (NH4)2H3(PO4)(SO4)-NH4H2PO4-H3PO4-H2O system.
T (°C) g1/100 g H2O (g1/100 g2) g2/100 g H2O (g1/100 g2) g3/100 g H2O (g1/100 g2)
25.0 19.3 132.7 0.0
25.0 21.6 113.9 8.31
25.0 25.2 79.2 23.3
25.0 36.7 58.1 33.0
25.0 68.4 37.1 53.7
70.0 74.5 234.6 0.0
70.0 70.1 217.9 3.65
70.0 58.8 177.1 22.1
70.0 72.7 123.2 44.1

(a) The composition unit is: g/100g H2O.

Part 2. The compilers used the data in Part 1 to calculate the following values.
100w1 w2 100w3 100w4 m1 (mol/kg) m2 (mol/kg) m3 (mol/kg)
11.1 0.0 32.2 56.7 11.6 0.0 5.78
10.6 10.6 30.4 48.4 12.8 2.23 6.41
10.3 15.6 29.6 44.5 13.6 3.58 6.79
10.2 19.4 29.5 40.9 14.7 4.84 7.35
10.3 19.4 29.5 40.8 14.8 4.85 7.38
9.41 22.8 27.1 40.7 13.6 5.72 6.79
8.71 25.1 25.1 41.1 12.4 6.23 6.22
7.66 31.7 22.0 38.6 11.6 8.38 5.82
6.19 40.6 17.8 35.4 10.3 11.7 5.13
4.72 52.3 13.6 29.4 9.42 18.2 4.71
4.07 58.6 11.7 25.6 9.34 23.4 4.67
3.43 64.4 9.87 29.5 6.82 29.5 3.41
12.3 0.0 35.5 52.2 13.9 0.0 6.93
11.8 9.46 33.9 44.8 15.4 2.15 7.71
11.5 17.3 33.1 38.1 17.7 4.63 8.86
11.4 23.9 32.7 32.0 20.9 7.62 10.4
11.3 27.3 32.7 28.7 23.2 9.71 11.6
11.4 29.6 32.8 26.2 25.5 11.5 12.8
11.2 30.3 32.2 26.3 25.0 11.8 12.5
10.9 31.3 31.3 26.5 24.1 12.1 12.1
9.95 36.3 28.7 25.1 23.3 14.8 11.6
9.05 41.2 26.1 23.7 22.4 17.7 11.2
7.89 47.7 22.7 21.7 21.3 22.4 10.7
7.29 52.0 21.0 19.7 21.7 26.9 10.9
6.21 59.9 17.9 16.0 22.8 38.2 11.4
10.7 0.0 30.7 58.6 10.7 0.0 5.34
10.3 4.72 29.7 55.3 10.9 8.73 x 10-1 5.47
9.81 11.2 28.2 50.7 11.4 2.26 5.68
9.61 14.8 27.7 47.9 11.8 3.15 5.89
9.14 16.4 26.3 48.1 11.2 3.48 5.58
8.13 19.4 23.4 49.0 9.75 4.05 4.87
7.68 22.1 22.1 48.1 9.38 4.69 4.69
11.1 0.0 32.1 56.8 11.5 0.0 5.77
10.6 10.6 30.4 48.4 12.8 2.23 6.4
10.3 18.0 29.6 42.1 14.3 4.36 7.17
10.2 19.4 29.5 40.9 14.7 4.85 7.35
10.2 19.4 29.5 40.9 14.7 4.84 7.36
9.4 22.1 27.1 41.4 13.3 5.44 6.66
8.72 25.1 25.1 41.1 12.5 6.23 6.23
11.5 0.0 33.2 55.3 12.2 0.0 6.11
11.0 10.3 31.5 47.2 13.6 2.23 6.82
10.8 18.0 31.0 40.3 15.7 4.55 7.83
10.6 23.0 30.4 36.0 17.2 6.53 8.61
10.6 23.0 30.4 36.1 17.2 6.49 8.58
9.98 25.1 28.7 36.2 16.2 7.09 8.1
9.44 27.2 27.2 36.2 15.3 7.65 7.65
12.3 0.0 35.4 52.2 13.8 0.0 6.92
11.8 9.47 33.9 44.8 15.4 2.16 7.72
11.5 17.3 33.1 38.1 17.7 4.62 8.85
11.4 23.9 32.7 32.0 20.8 7.62 10.4
11.3 27.3 32.7 28.7 23.2 9.7 11.6
11.4 29.6 32.8 26.2 25.6 11.5 12.8
11.2 30.3 32.2 26.3 25.0 11.8 12.5
10.9 31.3 31.3 26.5 24.1 12.1 12.1
13.1 0.0 37.8 49.1 15.7 0.0 7.84
12.4 16.1 35.6 35.9 20.2 4.58 10.1
12.0 25.7 34.6 27.7 25.5 9.48 12.7
12.0 29.8 34.6 23.6 29.9 12.9 15.0
12.2 32.4 35.1 20.3 35.3 16.3 17.7
12.4 33.9 35.7 18.0 40.4 19.2 20.2
12.5 34.6 36.0 16.9 43.5 20.9 21.8
12.5 34.5 36.1 16.9 43.5 20.9 21.8
12.4 35.0 35.6 17.0 42.7 21.0 21.4
12.3 35.4 35.4 16.9 42.6 21.3 21.3
8.93 28.9 22.4 39.7 13.2 7.44 5.775
8.17 30.8 19.7 41.4 11.6 7.59 4.868
6.79 34.5 14.8 43.9 9.07 8.01 3.441
6.16 39.1 10.9 43.9 8.24 9.08 2.525
6.02 49.3 6.1 38.6 9.17 13.0 1.612
11.2 39.9 24.4 24.4 26.9 16.7 10.2
10.9 39.9 23.7 25.5 25.0 15.9 9.49
9.75 41.2 21.1 27.9 20.5 15.1 7.7
8.53 46.6 15.4 29.4 17.0 16.2 5.35

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