IUPAC-NIST Solubilities Database

IUPAC-NIST Solubility Database
NIST Standard Reference Database 106

Solubility System: Ammonium dihydrogenphosphate with Diammonium hydrogenphosphate, Ammonium nitrate, Potassium sulfate 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) Diammonium hydrogenphosphate; (NH4)2HPO4; [7783-28-0]  NIST Chemistry WebBook for detail
   (4) Potassium sulfate; K2SO4; [7778-80-5]  NIST Chemistry WebBook for detail
   (5) Water; H2O; [7732-18-5]  NIST Chemistry WebBook for detail

Original Measurements:
   Babenko, A.M.; Andrianov, A.M., Zh. Prikl. Khim. (Leningrad) 57, 1921-5 (1984).

Variables:

   Concentration = Temperature and concentration of NH₄NO₃ and K₂SO₄ in a mixture containing a mol ratio of NH₄H₂PO₄/(NH₄)₂HPO₄ = 1.

Prepared By:
   J. Eysseltová

Experimental Data:   (Notes on the Nomenclature)
(Please see footnotes following the table(s).)

Part 1. Points of simultaneous crystallization of two or three solid phases in the NH₄H₂PO₄-(NH₄)₂HPO₄-NH₄NO₃-K₂SO₄-H₂O system
t/°C	Chemical₁	10² * Mass Fraction w₁^(b)	m₁ [mol/kg]^(b)	Chemical₂	10² * Mass Fraction w₂^(b)	Chemical₃	10² * Mass Fraction w₃^(b)	Chemical₄	10² * Mass Fraction w₄^(b)	m₄ [mol/kg]^(b)	Chemical₅	10² * Mass Fraction w₅^(b)	m₅ [mol/kg]^(b)	Chemical₆	10² * Mass Fraction w₆^(b)	Solid Phase(s)^(c)
-7.5	mixture	8.5	0.5	NH4H2PO4	4.0	(NH4)2HPO4	4.5	NH4NO3	9.9	1.7	K2SO4	8.0	0.6	H2O	73.6	A + B
-11.0	mixture	13.2	0.8	NH4H2PO4	6.1	(NH4)2HPO4	7.1	NH4NO3	15.2	2.9	K2SO4	5.0	0.4	H2O	66.6	A + B
-6.0	mixture	17.7	1.3	NH4H2PO4	8.2	(NH4)2HPO4	9.5	NH4NO3	20.3	4.4	K2SO4	5.0	0.5	H2O	57.0	B + C
14.0	mixture	19.2	1.5	NH4H2PO4	8.9	(NH4)2HPO4	10.3	NH4NO3	22.1	5.4	K2SO4	8.0	0.9	H2O	50.7	B + C
26.5	mixture (a)	20.7	1.9	NH4H2PO4	9.6	(NH4)2HPO4	11.1	NH4NO3	23.8	6.7	K2SO4	11.0	1.4	H2O	44.5	B + C
-11.8	mixture	16.7	1.1	NH4H2PO4	7.8	(NH4)2HPO4	8.9	NH4NO3	19.3	3.8	K2SO4	0.0	0.0	H2O	64.0	A + B + C
9.0	mixture	8.0	0.5	NH4H2PO4	3.7	(NH4)2HPO4	4.3	NH4NO3	9.3	1.7	K2SO4	13.0	1.1	H2O	69.7	B + D
14.5	mixture	12.2	0.8	NH4H2PO4	5.7	(NH4)2HPO4	6.5	NH4NO3	14.0	2.9	K2SO4	12.6	1.2	H2O	61.2	B + D
20.0	mixture	16.3	1.3	NH4H2PO4	7.6	(NH4)2HPO4	8.7	NH4NO3	18.7	4.4	K2SO4	12.5	1.4	H2O	52.5	B + D
25.0	mixture	18.4	1.6	NH4H2PO4	8.6	(NH4)2HPO4	9.8	NH4NO3	21.2	5.5	K2SO4	12.5	1.5	H2O	47.9	B + D
29.0	mixture	20.4	1.9	NH4H2PO4	9.5	(NH4)2HPO4	10.9	NH4NO3	23.6	6.7	K2SO4	12.0	1.6	H2O	44.0	B + C + D
-1.6	mixture	0.0	0.0	NH4H2PO4	0.0	(NH4)2HPO4	0.0	NH4NO3	0.0	0.0	K2SO4	6.5	0.4	H2O	93.5	A + D

Part 2. Solubility isotherms in the NH₄H₂PO₄-(NH₄)₂HPO₄-NH₄NO₃-K₂SO₄-H₂O system.
t/°C	Chemical₁	Mass Fraction w₁^(c)	Chemical₂	Mass Fraction w₂^(c)	m₂^(c)	Chemical₃	Mass Fraction w₃^(c)	Chemical₄	Mass Fraction w₄^(c)	Chemical₅	Mass Fraction w₅^(c)	m₅^(c)	Chemical₆	Mass Fraction w₆^(c)	m₆^(c)	Chemical₇	m₇^(c)
-5	S (a)	19.0	mixture (b)	8.5	0.5	NH4H2PO4	4.0	(NH4)2HPO4	4.5	NH4NO3	9.8	1.7	K2SO4	8.6	0.7	H2O	73.1
-5	S (a)	21.5	mixture (b)	13.1	0.8	NH4H2PO4	6.1	(NH4)2HPO4	7.0	NH4NO3	15.1	2.9	K2SO4	6.0	0.5	H2O	65.8
-5	S (a)	20.4	mixture (b)	17.9	1.2	NH4H2PO4	8.3	(NH4)2HPO4	9.6	NH4NO3	20.6	4.2	K2SO4	0.0	0.0	H2O	61.5
-5	S (a)	25.8	mixture (b)	17.6	1.3	NH4H2PO4	8.2	(NH4)2HPO4	9.4	NH4NO3	20.3	4.5	K2SO4	5.2	0.5	H2O	56.9
0	S (a)	20.4	mixture (b)	8.4	0.5	NH4H2PO4	3.9	(NH4)2HPO4	4.5	NH4NO3	9.6	1.7	K2SO4	10.0	0.8	H2O	72.0
0	S (a)	21.2	mixture (b)	18.6	1.3	NH4H2PO4	8.7	(NH4)2HPO4	9.9	NH4NO3	21.4	4.5	K2SO4	0.0	0.0	H2O	60.0
0	S (a)	22.6	mixture (b)	12.9	0.8	NH4H2PO4	6.0	(NH4)2HPO4	6.9	NH4NO3	14.9	2.9	K2SO4	7.3	0.6	H2O	64.9
0	S (a)	26.5	mixture (b)	17.4	1.2	NH4H2PO4	8.1	(NH4)2HPO4	9.3	NH4NO3	20.2	4.5	K2SO4	6.0	0.6	H2O	56.4
10	S (a)	25.6	mixture (b)	12.5	0.8	NH4H2PO4	5.8	(NH4)2HPO4	6.7	NH4NO3	14.4	2.9	K2SO4	10.5	1.0	H2O	62.6
10	S (a)	23.1	mixture (b)	20.2	1.4	NH4H2PO4	9.4	(NH4)2HPO4	10.8	NH4NO3	23.3	5.2	K2SO4	0.0	0.0	H2O	56.5
10	S (a)	29.1	mixture (b)	16.9	1.3	NH4H2PO4	7.9	(NH4)2HPO4	9.0	NH4NO3	19.5	4.5	K2SO4	9.0	0.9	H2O	54.6

Notes:
   Table 1  ^a  "Mixture" is an equimolar mixture of NH₄H₂PO₄ and (NH₄)₂HPO₄.
   Table 1  ^b  W=100w_i, M=m_i/mol kg^–1. Mass fractions of the ammonium phosphates and all molalities were calculated by the compiler.
   Table 1  ^c  The solid phases are: A=ice; B=NH₄NO₃; C=NH₄H₂PO₄; D=K₂SO₄.
   Table 2  ^a  S is the total plant nutrient: (N+PO₅ + K₂O + S)
   Table 2  ^b  "Mixture" is an equimolar mixture of NH₄H₂PO₄ and (NH₄)₂HPO₄.
   Table 2  ^c  W=100w_i, M=m_i/mol kg^–1. Mass fractions of the ammonium phosphates and all molalities were calculated by the compiler.

Method/Apparatus/Procedure:
   An improved polythermic method¹ was used.

Source and Purity of Materials:
   Chemically pure or reagent grade salts were recrystallized twice and dried at 40 °C to 50 °C. The material designated "mixture" was prepared by mixing equimolar amounts of NH₄H₂PO₄ and (NH₄)₂HPO₄ and homogenizing by grinding in a mortar.

Estimated Errors:

   Temperature: Precision of temperature measurement was ±0.4 K.

References:
   ¹Erayzer, L.N.; Kaganskiy, I.M. Zavod. Lab. 1967, 1, 119.