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IUPAC-NIST Solubility Database
NIST Standard Reference Database 106
Solubility System:
Ammonium dihydrogenphosphate with Ammonium nitrate, Potassium dihydrogenphosphate, Potassium nitrate and Water
Components:
(1) Ammonium dihydrogenphosphate; NH4H2PO4; [7722-76-1]
NIST Chemistry WebBook
for detail
(2) Ammonium nitrate; NH4NO3; [6484-52-2]
NIST Chemistry WebBook
for detail
(3) Potassium dihydrogenphosphate; KH2PO4; [7778-77-0]
NIST Chemistry WebBook
for detail
(4) Potassium nitrate; KNO3; [7757-79-1]
NIST Chemistry WebBook
for detail
(5) Water; H2O; [7732-18-5]
NIST Chemistry WebBook
for detail
Original Measurements:
Bergman, A.G.; Opredelenkova, L.V.; Dzuev, A.B., Ukr. Khim. Zh. 33, 285 (1967).
Variables:
Concentration = Temperature and composition.
Prepared By:
J. Eysseltová
Experimental Data:
(Notes on the Nomenclature)
(Please see footnotes following the table(s).)
Crystallization temperature and composition of invariant points in the KNO
3
-NH
4
H
2
PO
4
-H
2
O system.
t/°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
Solid Phase(s)
(b)
-7.7
KNO3
8.5
1.1
NH4H2PO4
15.5
1.77
H2O
76.0
A + B + C
5.5
KNO3
16.0
2.33
NH4H2PO4
16.0
2.05
H2O
68.0
B + C + D
40
KNO3
35.0
6.53
NH4H2PO4
12.0
1.97
H2O
53.0
B + D + E
16.5
KNO3
11.5
1.85
NH4H2PO4
27.0
3.82
H2O
61.5
C + D + F
92.5
KNO3
16.0
4.52
NH4H2PO4
49.0
12.2
H2O
35.0
D + E + F
Notes:
Table 1
a
These values were calculated by the compiler.
Table 1
b
The solid phases are: A=ice; B=α-KNO
3
; C=α-NH
4
H
2
PO
4
; D="unidentified conversion product":; E=β-KNO
3
; F=β-NH
4
H
2
PO
4
.
Method/Apparatus/Procedure:
A polythermic method was used.
1
The appearance of the first crystals as well as the disappearance of the last crystals was recorded.
Source and Purity of Materials:
Reagent grade KNO
3
and NH
4
H
2
PO
4
were recrystallized and dried before being used. Their melting points were 337 °C and 200 °C, respectively.
Estimated Errors:
Solubility: No information given.
Temperature: The only information given is that the difference between the temperature of dissolution of the last crystal and appearance of the first crystal was kept to a minimum.
References:
1
A. G. Bergman and N. P. Luzhnaya, Fiziko-Khimicheskie Osnovy Izucheniya i Ispol'zovaniya Solyanykh Mestorozhdeniy Khlorid-Sul'fatnogo Tipa, Moscow, IAN SSSR (1951).