IUPAC-NIST Solubilities Database

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:
   Brosheer, J.C.; Anderson, J.F. Jr., J. Am. Chem. Soc. 1946, 68, 902.

Variables:

   Concentration = Composition at 60 ºC and 75 ºC

Prepared By:
   J. Eysseltová

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

Table I. Solubility in the NH₃-H₃PO₄-H₂O system at 75 °C. The solid phase was determined by microscopic examination.
Chemical₁	10² * Mass Fraction w₁	m₁ [mol/kg]^(a)	Chemical₂	10² * Mass Fraction w₂	m₂ [mol/kg]^(a)	Chemical₃	10² * Mass Fraction w₃^(a)	Solid Phase(s)^(b)
NH3	6.75	13.49	H3PO4	63.86	22.17	H2O (a)	29.39	A
NH3	6.87	11.52	H3PO4	58.11	16.93	H2O (a)	35.02	A
NH3	6.98	10.73	H3PO4	54.81	14.64	H2O (a)	38.21	A
NH3	7.02	10.76	H3PO4	54.67	14.56	H2O (a)	38.31	A
NH3	7.25	9.91	H3PO4	49.79	11.83	H2O (a)	42.96	A
NH3	7.23	9.47	H3PO4	47.96	10.92	H2O (a)	44.81	A
NH3	7.48	9.29	H3PO4	45.25	9.77	H2O (a)	47.27	A
NH3	7.71	9.46	H3PO4	44.42	9.47	H2O (a)	47.87	A
NH3	7.81	9.62	H3PO4	44.54	9.54	H2O (a)	47.65	A
NH3	7.80	9.68	H3PO4	44.86	9.67	H2O (a)	47.34	A
NH3	8.11	10.14	H3PO4	44.91	9.75	H2O (a)	46.98	A
NH3	8.20	10.31	H3PO4	45.11	9.86	H2O (a)	46.69	A
NH3	8.53	10.85	H3PO4	45.31	10.02	H2O (a)	46.16	A
NH3	9.22	12.37	H3PO4	47.02	10.96	H2O (a)	43.76	A
NH3	9.27	12.50	H3PO4	47.17	11.05	H2O (a)	43.56	A
NH3	9.60	13.27	H3PO4	47.93	11.52	H2O (a)	42.47	A
NH3	9.82	13.69	H3PO4	48.05	11.64	H2O (a)	42.13	A
NH3	9.90	13.85	H3PO4	48.13	11.70	H2O (a)	41.97	A
NH3	10.54	15.58	H3PO4	49.73	12.77	H2O (a)	39.73	A
NH3	11.09	17.20	H3PO4	51.06	13.77	H2O (a)	37.85	A
NH3	11.34	17.97	H3PO4	51.61	14.21	H2O (a)	37.05	A
NH3	11.52	18.54	H3PO4	52.00	14.55	H2O (a)	36.48	A
NH3	12.07	20.44	H3PO4	53.25	15.67	H2O (a)	34.68	A
NH3	12.50	21.96	H3PO4	54.07	16.50	H2O (a)	33.43	A
NH3	13.04	24.00	H3PO4	55.05	17.60	H2O (a)	31.91	A
NH3	13.14	24.83	H3PO4	55.79	18.32	H2O (a)	31.07	A
NH3	14.10	29.34	H3PO4	57.68	20.86	H2O (a)	28.22	A
NH3	14.34	30.65	H3PO4	58.19	21.62	H2O (a)	27.47	A
NH3	14.39	31.07	H3PO4	58.41	21.91	H2O (a)	27.20	A
NH3	14.61	31.96	H3PO4	58.55	22.26	H2O (a)	26.84	A
NH3	17.89	25.91	H3PO4	59.23	26.42	H2O (a)	25.88	A + B
NH3	14.70	30.34	H3PO4	56.85	20.39	H2O (a)	28.45	B
NH3	14.47	26.15	H3PO4	53.04	16.66	H2O (a)	32.49	B
NH3	14.24	23.34	H3PO4	49.93	14.22	H2O (a)	35.83	B
NH3	13.82c	20.44	H3PO4	46.48 (c)	11.95	H2O (a)	39.70	B
NH3	13.58	17.76	H3PO4	41.53	9.44	H2O (a)	44.89	B
NH3	13.42	16.61	H3PO4	39.13	8.41	H2O (a)	47.45	B
NH3	13.38	16.39	H3PO4	38.69	8.24	H2O (a)	47.93	B

Table II. Solubility in the NH₃-H₃PO₄-H₂O system at 75 °C. The solid phase was determined by the Schreinemakers' method.
Chemical₁	10² * Mass Fraction w₁	m₁ [mol/kg]^(a)	Chemical₂	10² * Mass Fraction w₂	m₂ [mol/kg]^(a)	Chemical₃	10² * Mass Fraction w₃^(a)	Solid Phase(s)^(b)
NH3	6.85	31.42	H3PO4	80.35	64.05	H2O	12.80	A
NH3	6.72	21.87	H3PO4	75.24	42.56	H2O	18.04	A
NH3	13.55c	16.24c	H3PO4	37.46	7.80	H2O	48.99	B + C
NH3	12.88	14.68	H3PO4	35.61	7.05	H2O	51.51	C
NH3	12.47	13.43	H3PO4	33.02	6.18	H2O	54.51	C
NH3	12.08	12.16	H3PO4	29.57	5.17	H2O	58.35	C
NH3	11.91	11.48	H3PO4	27.16	4.55	H2O	60.93	C
NH3	11.98	11.30	H3PO4	25.74	4.22	H2O	62.28	C
NH3	11.83	10.59	H3PO4	22.60	3.52	H2O	65.57	C
NH3	11.94	10.43	H3PO4	20.86	3.17	H2O	67.20	C
NH3	12.15	9.79	H3PO4	14.96	2.09	H2O	72.89	C
NH3	13.47	10.18	H3PO4	8.86	1.16	H2O	77.67	C
NH3	15.40	11.41	H3PO4	5.36	0.690	H2O	79.24	C
NH3	20.47	15.49	H3PO4	1.92	0.252	H2O	77.61	C
NH3	23.73	18.53	H3PO4	1.09	0.148	H2O	75.18	C

Table III. Solubility in the NH₃-H₃PO₄-H₂O system at 60 °C. The solid phase was determined by the Schreinemakers' method.
Chemical₁	10² * Mass Fraction w₁	m₁ [mol/kg]^(a)	Chemical₂	10² * Mass Fraction w₂	m₂ [mol/kg]^(a)	Chemical₃	10² * Mass Fraction w₃^(a)	Solid Phase(s)^(b)
NH3	12.74	16.26	H3PO4	41.24	9.14	H2O	46.02	B
NH3	12.36	14.61	H3PO4	37.96	7.80	H2O	49.68	B
NH3	12.45	14.39	H3PO4	36.76	7.39	H2O	50.79	B
NH3	12.54	14.28	H3PO4	35.90	7.10	H2O	51.56	B
NH3	12.62	14.34	H3PO4	35.69	7.05	H2O	51.69	B + C
NH3	12.64	14.34	H3PO4	35.61	7.02	H2O	51.75	B + C
NH3	11.72	12.04	H3PO4	31.13	5.56	H2O	57.15	C
NH3	11.04	10.29	H3PO4	25.98	4.21	H2O	62.98	C

Notes:
   Table 1  ^a  These values were calculated by the compiler.
   Table 1  ^b  The solid phases are A=NH₄H₂PO₄; B=(NH₄)₂HPO₄.
   Table 1  ^c  This is the average of five determinations.
   Table 3  ^a  These values were calculated by the compiler.
   Table 3  ^b  The solid phases are: a=NH₄H₂PO₄; B=(NH₄)₂HPO₄; C=(NH₄)₇(PO₄) or (NH₄)₃PO₄·2((NH₄)₂HPO₄.
   Table 3  ^c  This is the average of four determinations.

Method/Apparatus/Procedure:
   Mixtures were placed in 300 ml glass-stoppered bottles which were rotated end-over-end in a constant temperature bath for at least 3 days. Mixtures in which the vapor pressure of NH₃ prevented accurate sampling from open flasks were placed in special flasks for use under pressure. Aliquots of HCl solns of the samples were analyzed for NH₃ by addition of alkali and distillation into standard acid. Other aliquots were analyzed for H₃PO₄ by double precipitation as NH₄MgPO₄·6H₂O and ignition to Mg₂P₂O₇.

Source and Purity of Materials:
   Reagent grade H₃PO₄, monoammonium phosphate, diammonium phosphate and aqueous ammonia were used. Recrystallization did not alter the solubility of the salts.

Estimated Errors:

   Temperature: The temperature was kept constant to within ±0.05 K. Duplicate results were accepted only when they agreed within 0.5 %.