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IUPAC-NIST Solubility Database
NIST Standard Reference Database 106
Solubility System:
Ammonia with Phosphoric acid and Water
Components:
(1) Ammonia; NH3; [7664-41-7]
NIST Chemistry WebBook
for detail
(2) Phosphoric acid; H3PO4; [7664-38-2]
NIST Chemistry WebBook
for detail
(3) Water; H2O; [7732-18-5]
NIST Chemistry WebBook
for detail
Original Measurements:
Chernova, K.S., Izv. Sektora Fiz.-Khim. Analiza, Inst. Obshch. Neorg. Khim. Akad. Nauk SSSR 1947, 15, 112.
Variables:
Concentration = Composition at 0 ºC in the region where (NH
4
)
2
HPO
4
·2H
2
O and (NH
4
)
2
HPO
4
are the solid equilibrium phases.
Prepared By:
J. Eysseltová
Experimental Data:
(Notes on the Nomenclature)
(Please see footnotes following the table(s).)
Solubility in the crystallization field of (NH
4
)
2
HPO
4
·2H
2
O in the (NH
4
)
3
PO
4
-H
3
PO
4
-H
2
O system at 0 °C.
Chemical
1
10
2
* Mass Fraction w
1
m
1
[mol/kg]
(a)
Chemical
2
10
2
* Mass Fraction w
2
m
2
[mol/kg]
(a)
Chemical
3
10
2
* Mass Fraction w
3
(a)
Solid Phase(s)
(b)
NH3
9.35
8.62
H3PO4
26.95
4.32
H2O
63.70
A
NH3
7.80
6.58
H3PO4
22.60
3.31
H2O
69.60
B
NH3
7.38
6.03
H3PO4
20.79
2.95
H2O
71.83
B
NH3
8.38
7.53
H3PO4
26.31
4.11
H2O
65.31
B
NH3
8.31
7.49
H3PO4
26.52
4.15
H2O
65.17
B
NH3
9.25
9.00
H3PO4
30.40
5.14
H2O
60.35
B
NH3
9.50
9.52
H3PO4
31.93
5.56
H2O
58.57
B
NH3
-
-
H3PO4
32.20c
-
H2O
-
B
NH3
9.85
10.17
H3PO4
33.30
5.98
H2O
56.85
B
NH3
10.04
10.58
H3PO4
34.24
6.27
H2O
55.72
B
NH3
10.12
10.88
H3PO4
35.26
6.59
H2O
54.62
B
NH3
10.71
12.22
H3PO4
37.84
7.50
H2O
51.45
A
NH3
11.14
13.68
H3PO4
41.06
8.77
H2O
47.80
A + C
Notes:
Table 1
a
These values were calculated by the compiler.
Table 1
b
The solid phases are: A=(NH
4
)
2
HPO
4
; B=(NH
4
)
2
HPO
4
·2H
2
O; C=NH
4
H
2
PO
4
.
Table 1
c
The meaning of this point is not clear. The compiler assumes it is a parallel analysis of H
3
PO
4
in the solution above.
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 (NH
4
)
2
HPO
4
was recrystallized from a solution containing a small excess of ammonia. No other information is given.
Estimated Errors:
Solubility: No information is given.
Temperature: No information is given.