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:
   Parker, E.G., J. Phys. Chem. 1914, 18, 653.

Variables:

   Concentration = Composition at 25 ºC.

Prepared By:
   J. Eysseltová

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

Solubility in the (NH₄)₃PO₄-NH₃-H₃PO₄-H₂O system at 25 °C.

Chemical1	m1 [mol/kg](b)	Chemical2	m2 [mol/kg](b)	Chemical3	102 * Mass Fraction w3(a)	m3 [mol/kg](a)	Chemical4	102 * Mass Fraction w4(a)	m4 [mol/kg](a)	Chemical5	102 * Mass Fraction w5(a)	Solid Phase(s)(c)
NH3	2.77	H3PO4	6.09	NH3	4.72	8.22	H3PO4	61.57	18.63	H2O	33.72	A
NH3	2.75	H3PO4	5.44	NH3	4.68	6.82	H3PO4	55.00	13.92	H2O	40.32	A
NH3	2.50	H3PO4	4.61	NH3	4.26	5.09	H3PO4	46.60	9.68	H2O	49.14	A
NH3	2.40	H3PO4	3.62	NH3	4.09	4.05	H3PO4	36.60	6.30	H2O	59.32	A
NH3	2.45	H3PO4	2.64	NH3	4.17	3.54	H3PO4	26.69	3.94	H2O	69.14	A
NH3	2.58	H3PO4	2.57	NH3	4.39	3.71	H3PO4	25.98	3.81	H2O	69.62	A
NH3	2.58	H3PO4	2.67	NH3	4.39	3.76	H3PO4	26.99	4.01	H2O	68.61	A
NH3	4.04	H3PO4	3.30	NH3	6.88	6.76	H3PO4	33.36	5.70	H2O	59.76	A
NH3	5.23	H3PO4	3.77	NH3	8.91	9.87	H3PO4	38.11	7.34	H2O	52.98	A
NH3	7.21	H3PO4	4.75	NH3	12.28	18.16	H3PO4	48.02	12.34	H2O	39.70	A
NH3	7.30	H3PO4	4.76	NH3	12.43	18.51	H3PO4	48.12	12.45	H2O	39.45	B
NH3	7.01	H3PO4	4.38	NH3	11.94	16.01	H3PO4	44.28	10.32	H2O	43.78	B
NH3	6.90	H3PO4	3.95	NH3	11.75	14.28	H3PO4	39.93	8.43	H2O	48.32	B
NH3	6.27	H3PO4	3.41	NH3	10.68	11.43	H3PO4	34.47	6.41	H2O	54.85	C
NH3	4.28	H3PO4	2.57	NH3	7.29	6.41	H3PO4	25.98	3.97	H2O	66.73	C
NH3	4.19	H3PO4	1.83	NH3	7.14	5.63	H3PO4	18.50	2.54	H2O	74.36	C
NH3	6.59	H3PO4	1.33	NH3	11.22	8.75	H3PO4	13.45	1.82	H2O	75.33	C
NH3	8.75	H3PO4	0.87	NH3	14.90	11.47	H3PO4	8.80	1.18	H2O	76.30	C
NH3	11.48	H3PO4	0.43	NH3	19.55	15.08	H3PO4	4.35	0.58	H2O	76.10	C
NH3	14.08	H3PO4	0.41	NH3	23.98	19.59	H3PO4	4.14	0.59	H2O	71.88	C

Notes:
   Table 1  ^a  All these values were calculated by the compiler
   Table 1  ^b  The compositions unit is: mol/1000 g of the solution.
   Table 1  ^c  The solid phases are: A=NH₄H₂PO₄·H₂O; B= (NH₄)₂HPO₄; C=(NH₄)₃PO₄.

Method/Apparatus/Procedure:
   Bottles containing mixtures of ammonia and orthophosphoric acid and in contact with a solid phase were allowed to rotate in a thermostat until equilibrium was established. Ammonia and phosphorus were determined by methods described elsewhere.¹

Source and Purity of Materials:
   No information is given.

Estimated Errors:


References:
   ¹F. P. Treadwell and W. T. Hall, Analytical Chemistry, Vol II, 59 , 434 (1913).

---

Distributed by the Office of Data and Informatics of the National Institute of Standards and Technology (NIST) Material Measurement Laboratory (MML).
Website is owned by NIST (an agency of the U.S. Department of Commerce)

---

Last updated: February 18, 2015 (Created: August 17, 2007)