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IUPAC-NIST Solubility Database
NIST Standard Reference Database 106
Solubility System:
Ammonium dihydrogenphosphate with Urea and Water
Components:
(1) Ammonium dihydrogenphosphate; NH4H2PO4; [7722-76-1]
NIST Chemistry WebBook
for detail
(2) Urea; CH4N2O; [57-13-6]
NIST Chemistry WebBook
for detail
(3) 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 Remarks:
Remarks: ADDITIONAL DATA: Solubility polytherm and solubility isotherms in the temperature range –10 ºC to +50 ºC are given, but only in graphical form. Relative areas of crystallization fields are: ice = 9.98 %, α-NH
4
H
2
PO
4
= 8.01 %; β-NH
4
H
2
PO
4
= 62.18 %; -α-CO(NH
2
)
2
= 4.99 %; β-CO(NH
2
)
2
= 2.28 %; γ-CO(NH
2
)
2
= 12.56 %.
Experimental Data:
(Notes on the Nomenclature)
(Please see footnotes following the table(s).)
Composition and crystallization temperature of invariant points in the NH
4
H
2
PO
4
-CO(NH
2
)
2
-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)
-17.5
CO(NH2)2
30.0
8.84
NH4H2PO4
13.5
2.08
H2O
56.5
A + B + C
-6.0
CO(NH2)2
35.0
11.5
NH4H2PO4
14.5
2.50
H2O
50.5
B + C + D
28.0
CO(NH2)2
51.5
25.6
NH4H2PO4
15.0
3.89
H2O
33.5
C + D + E
46.0
CO(NH2)2
58.0
35.8
NH4H2PO4
15.0
4.83
H2O
27.0
D + E + F
Notes:
Table 1
a
The molality values were calculated by the compiler.
Table 1
b
The solid phases are: A=ice; B=α-NH
4
H
2
PO
4
; C=α-CO(NH
2
)
2
; D=β-NH
4
H
2
PO
4
; E=β-CO(NH
2
)
2
; F=γ-CO(NH
2
)
2
.
Method/Apparatus/Procedure:
A visual polythermic method was used.
1
The appearance of the first crystals as well as the disappearance of the last crystals was observed, the difference between these values being kept to a minimum.
Source and Purity of Materials:
Reagent grade urea and NH
4
H
2
PO
4
were recrystallized and dried before being used. Their melting points were 132.5 °C and 200 °C, respectively.
Estimated Errors:
Solubility: No information is given.
Temperature: No information is given.
References:
1
Bergman, A.G.; Luzhnaya, N.P. Fiziko-Khimicheskie Osnovy Izucheniya i Ispol'zovaniya Solyanykh Mestorozhdeniy Khlorid-Sul'fatnogo Tipa, Moscow, IAN SSSR, 1951.