IUPAC-NIST Solubilities Database

IUPAC-NIST Solubility Database
NIST Standard Reference Database 106

Solubility System: Ammonium dihydrogenphosphate with Diammonium dihydrogendiphosphate and Water

Components:
   (1) Ammonium dihydrogenphosphate; NH4H2PO4; [7722-76-1]  NIST Chemistry WebBook for detail
   (2) Diammonium dihydrogendiphosphate; (NH4)2H2P2O7; [13597-86-9]  NIST Chemistry WebBook for detail
   (3) Water; H2O; [7732-18-5]  NIST Chemistry WebBook for detail

Original Measurements:
   Chulanova, G.A.; Mukhina, L.S.; Shipyatskaya, R.I.; Taran, A.I., Zh. Prikl. Khim. (Leningrad) 1976, 49, 1933.

Variables:

   Concentration = Composition at 50 °C and 70 °C

Prepared By:
   J. Eysseltová

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


t/°C	Chemical₁	10² * Mass Fraction w₁	m₁ [mol/kg]^(a)	Chemical₂	10² * Mass Fraction w₂	m₂ [mol/kg]^(a)	Chemical₃	10² * Mass Fraction w₃	m₃ [mol/kg]	Chemical₄	m₄ [mol/kg]	Solid Phase(s)^(b)
50	(NH4)2H2P2O7	0.0	0.0	NH4H2PO4	40.5	5.92	H2O (a) pyro-P2O5	59.5	0.0	ortho-P2O5	2.96	A
50	(NH4)2H2P2O7	6.3	0.53	NH4H2PO4	37.7	5.85	H2O (a) pyro-P2O5	56.0	0.53	ortho-P2O5	2.93	A
50	(NH4)2H2P2O7	9.1	0.79	NH4H2PO4	36.4	5.81	H2O (a) pyro-P2O5	54.5	0.79	ortho-P2O5	2.90	A
50	(NH4)2H2P2O7	16.3	1.51	NH4H2PO4	32.7	5.57	H2O (a) pyro-P2O5	51.0	1.51	ortho-P2O5	2.78	A
50	(NH4)2H2P2O7	26.7	2.70	NH4H2PO4	26.7	4.98	H2O (a) pyro-P2O5	46.6	2.72	ortho-P2O5	2.50	A
50	(NH4)2H2P2O7	34.8	3.91	NH4H2PO4	23.2	4.80	H2O (a) pyro-P2O5	42.0	3.91	ortho-P2O5	2.40	A
50	(NH4)2H2P2O7	40.0	4.72	NH4H2PO4	20.0	4.35	H2O (a) pyro-P2O5	40.0	4.72	ortho-P2O5	2.17	A
50	(NH4)2H2P2O7	48.0	6.29	NH4H2PO4	16.0	3.86	H2O (a) pyro-P2O5	36.0	6.29	ortho-P2O5	1.53 (c)	B
50	(NH4)2H2P2O7	51.0	6.64	NH4H2PO4	12.8	3.07	H2O (a) pyro-P2O5	36.2	6.65	ortho-P2O5	1.53	B
50	(NH4)2H2P2O7	53.6	6.74	NH4H2PO4	8.9	2.1	H2O (a) pyro-P2O5	37.5	6.74	ortho-P2O5	1.03	B
50	(NH4)2H2P2O7	61.0	7.38	NH4H2PO4	0.0	0.0	H2O (a) pyro-P2O5	39.0	7.38	ortho-P2O5	0.00	B

Table 2. Solubility values for the (NH₄)₂H₂P₂O₇-NH₄H₂PO₄-H₂O system.
t/°C	Chemical₁	10² * Mass Fraction w₁	m₁ [mol/kg]^(a)	Chemical₂	10² * Mass Fraction w₂	m₂ [mol/kg]^(a)	Chemical₃	10² * Mass Fraction w₃	m₃ [mol/kg]	Chemical₄	m₄ [mol/kg]	Solid Phase(s)^(b)
70	(NH4)2H2P2O7	0.0	0.0	NH4H2PO4	49.5	8.52	H2O (a) pyro-P2O5	50.5	0.0	ortho-P2O5	4.26	A
70	(NH4)2H2P2O7	7.5	0.74	NH4H2PO4	45.0	8.24	H2O (a) pyro-P2O5	47.5	0.74	ortho-P2O5	4.12	A
70	(NH4)2H2P2O7	10.8	1.10	NH4H2PO4	43.0	8.09	H2O (a) pyro-P2O5	46.2	1.10	ortho-P2O5	4.04	A
70	(NH4)2H2P2O7	19.0	2.08	NH4H2PO4	38.0	7.68	H2O (a) pyro-P2O5	43.0	2.08	ortho-P2O5	3.84	A
70	(NH4)2H2P2O7	31.1	3.88	NH4H2PO4	31.1	7.15	H2O (a) pyro-P2O5	37.8	3.88	ortho-P2O5	3.57	A
70	(NH4)2H2P2O7	39.0	5.25	NH4H2PO4	26.0	6.46	H2O (a) pyro-P2O5	35.0	5.26	ortho-P2O5	3.23	A
70	(NH4)2H2P2O7	44.9	6.47	NH4H2PO4	22.4	5.95	H2O (a) pyro-P2O5	32.7	6.48	ortho-P2O5	3.00	A
70	(NH4)2H2P2O7	52.5	8.25	NH4H2PO4	17.5	5.07	H2O (a) pyro-P2O5	30.0	8.25	ortho-P2O5	2.53	B
70	(NH4)2H2P2O7	55.5	8.55	NH4H2PO4	13.9	3.95	H2O (a) pyro-P2O5	30.6	8.56	ortho-P2O5	1.97	B
70	(NH4)2H2P2O7	59.5	9.17	NH4H2PO4	9.9	2.8	H2O (a) pyro-P2O5	30.6	9.17	ortho-P2O5	1.40	B
70	(NH4)2H2P2O7	67.0	9.57	NH4H2PO4	0.0	0.0	H2O (a) pyro-P2O5	33.0	10.02	ortho-P2O5	0.00	B

Notes:
   Table 1  ^a  These values were calculated by the computer
   Table 1  ^b  The solid phases are: A=NH₄H₂PO₄: B=(NH₄)₂H₂P₂O₇.
   Table 1  ^c  This is an obvious error. The compiler thinks this value should be 1.9.3.
   Table 2  ^a  These values were calculated by the compiler.
   Table 2  ^b  The solid phases are: A=NH₄H₂PO₄: B=(NH₄)₂H₂P₂O₇.

Method/Apparatus/Procedure:
   The visual polythermic method was used. All experimental details are described in Ref (1).

Source and Purity of Materials:
   The only information given is that (NH₄)₂H₂P₂O₇ was prepared by heating (NH₄)₄P₂O₇ to 125 °C.

Estimated Errors:
   Solubility: No information is given.

References:
   ¹G. A. Chulanova, R. I. Shipyatskaya, and L. S. Mukhina, Zh. Prikl. Khim. (Leningrad) 47, 1637 (1974).