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IUPAC-NIST Solubility Database
NIST Standard Reference Database 106
Solubility System:
Ammonium dihydrogenphosphate with Ammonium nitrate, Urea nitrate, Urea phosphate 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) Urea nitrate; CO(NH2)2.HNO3; [17687-37-5]
NIST Chemistry WebBook
for detail
(4) Urea phosphate; CO(NH2)2.H3PO4; [4861-19-2]
NIST Chemistry WebBook
for detail
(5) Water; H2O; [7732-18-5]
NIST Chemistry WebBook
for detail
Original Measurements:
Kummel, R.; Fahsl, R., Z. Anorg. Allg. Chem. 1973, 402, 305.
Variables:
Concentration = Composition at 20 ºC and 40 ºC.
Prepared By:
J. Eysseltová
Experimental Data:
(Notes on the Nomenclature)
(Please see footnotes following the table(s).)
Table 1. Composition of invariant points in the NH
4
H
2
PO
4
-NH
4
NO
3
-CO(NH
2
)
2
.HNO
3
-CO(NH
2
)
2
·H
3
PO
4
-H
2
O system at
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
m
3
[mol/kg]
(a)
Chemical
4
10
2
* Mass Fraction w
4
Solid Phase(s)
(b)
20
CO(NH2)2.HNO3
15.26
3.245
CO(NH2)2.H3PO4
14.92
2.469
NH4H2PO4
31.59
7.183
H2O
38.23
A + B + C
40
CO(NH2)2.HNO3
19.53
6.255
CO(NH2)2.H3PO4
20.73
5.168
NH4H2PO4
34.36
11.77
H2O
25.38
A + B + C
Table 2
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
m
3
[mol/kg]
(a)
Chemical
4
10
2
* Mass Fraction w
4
Solid Phase(s)
(b)
20
NH4NO3
51.89
20.10
CO(NH2)2.HNO3
7.85
1.98
NH4H2PO4
8.01
1.57
H2O
32.25
A + C + D
40
NH4NO3
54.99
30.49
CO(NH2)2.HNO3
11.27
4.07
NH4H2PO4
11.21
3.15
H2O
22.53
A + C + D
Notes:
Table 1
a
The molalities were calculated by the compiler and are expressed as mol kg
–1
.
Table 1
b
The solid phases are: A=CO(NH
2
)
2
·HNO
3
; B=CO(NH
2
)
2
·H
3
PO
4
; C=NH
4
H
2
PO
4
; D=NH
4
NO
3
.
Method/Apparatus/Procedure:
Mixtures of the components were stirred vigorously and allowed to equilibrate for 15 hrs to 25 hrs. The equilibrium was checked by repeated analysis of the liquid phase. PO
4
3–
content was determined by precipitation titration with La(NO
3
)
3
using Chromazurol S as indicator; NH
4
+
was determined, after removal of phosphate ions with the aid of anion exchange resin, by formol tritration. Urea was determined gravimetrically as dixanthedrylurea or after enzyme decomposition as NH
3
. Nitrate was determined gravimetrically with Nitron. The sum of NH
4
+
and urea was determined by the Kjeldahl method and the concentration of urea salts was determined by acidimetric titration with a METROHM potentiograph.
Source and Purity of Materials:
The ammonium salts were recrystallized before use. The urea salts were synthesized from urea and an equivalent amount of the respective acid and recrystallized several times.
Estimated Errors:
Temperature: No information given.