IUPAC-NIST Solubilities Database

IUPAC-NIST Solubility Database
NIST Standard Reference Database 106

Solubility System: Ammonia with Diphosphoric acid and Water

Components:
   (1) Ammonia; NH3; [7664-41-7]  NIST Chemistry WebBook for detail
   (2) Diphosphoric acid; H4P2O7; [2466-09-3]  NIST Chemistry WebBook for detail
   (3) Water; H2O; [7732-18-5]  NIST Chemistry WebBook for detail

Original Measurements:
   Farr, T.D.; Fleming, J.D., J. Chem. Eng. Data 1965, 10. 20.

Variables:

   Concentration = Composition at 273 K and 298 K.

Prepared By:
   J. Eysseltová

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

Solubility in the NH₃-H₄P₂O₇-H₂O system at 273 K.
pH	Chemical₁	10² * Mass Fraction w₁	Chemical₂	10² * Mass Fraction w₂	Chemical₃	10² * Mass Fraction w₃	m₃ [mol/kg]	Chemical₄	10² * Mass Fraction w₄	m₄ [mol/kg]	Chemical₅	10² * Mass Fraction w₅	Solid Phase(s)^(b)
----	N	4.83	P2O5	22.59	NH3 (a)	5.87	5.24	H4P2O7 (a)	28.32	2.42	H2O (a)	65.80	A
4.80	N	7.66	P2O5	30.74	NH3 (a)	9.31	10.49	H4P2O7 (a)	38.54	4.15	H2O (a)	52.14	"
4.97	N	8.23	P2O5	32.24	NH3 (a)	10.00	11.85	H4P2O7 (a)	40.42	4.58	H2O (a)	49.57	"
5.09	N	8.96	P2O5	34.18	NH3 (a)	10.89	13.82	H4P2O7 (a)	42.83	5.20	H2O (a)	46.28	A + B
5.81	N	9.05	P2O5	31.02	NH3 (a)	11.00	12.89	H4P2O7 (a)	38.89	4.36	H2O (a)	50.10	B
----	N	9.24	P2O5	30.88	NH3 (a)	11.23	13.18	H4P2O7 (a)	38.72	4.35	H2O (a)	50.05	"
----	N	10.04	P2O5	31.42	NH3 (a)	12.21	14.81	H4P2O7 (a)	39.40	4.57	H2O (a)	48.40	"
6.50	N	10.33	P2O5	32.03	NH3 (a)	12.56	15.60	H4P2O7 (a)	40.16	4.77	H2O (a)	47.28	"
6.88	N	9.26	P2O5	27.36	NH3 (a)	11.26	12.14	H4P2O7 (a)	34.30	3.54	H2O (a)	54.44	B + D
7.80	N	7.75	P2O5	20.65	NH3 (a)	9.44	8.57	H4P2O7 (a)	25.89	2.25	H2O (a)	64.67	D
3.51	N	6.11	P2O5	28.85	NH3 (a)	7.43	7.73	H4P2O7 (a)	36.17	3.60	H2O (a)	56.40	A
4.66	N	8.33	P2O5	35.34	NH3 (a)	10.13	13.05	H4P2O7 (a)	44.31	5.46	H2O (a)	45.56	"
4.66	N	9.52	P2O5	38.89	NH3 (a)	11.58	17.13	H4P2O7 (a)	48.76	6.91	H2O (a)	39.66	"
4.84	N	11.05	P2O5	42.39	NH3 (a)	13.44	23.61	H4P2O7 (a)	53.15	8.94	H2O (a)	33.41	B
5.05	N	10.69	P2O5	40.27	NH3 (a)	13.00	20.90	H4P2O7 (a)	50.49	7.77	H2O (a)	36.51	"
5.30	N	10.49	P2O5	38.52	NH3 (a)	12.75	19.23	H4P2O7 (a)	48.30	6.97	H2O (a)	38.95	"
5.75	N	10.42	P2O5	37.21	NH3 (a)	12.67	18.29	H4P2O7 (a)	46.65	6.44	H2O (a)	40.68	"
5.91	N	10.61	P2O5	36.22	NH3 (a)	12.90	18.17	H4P2O7 (a)	45.41	6.12	H2O (a)	41.69	"
6.05	N	10.61	P2O5	35.81	NH3 (a)	12.90	17.95	H4P2O7 (a)	44.90	5.98	H2O (a)	42.20	"
----	N	11.29	P2O5	35.99	NH3 (a)	13.73	19.59	H4P2O7 (a)	45.13	6.16	H2O (a)	41.15	"
6.26	N	11.55	P2O5	36.60	NH3 (a)	14.04	20.58	H4P2O7 (a)	45.89	6.44	H2O (a)	40.07	B + C
6.40	N	11.14	P2O5	34.93	NH3 (a)	13.54	18.64	H4P2O7 (a)	43.80	5.77	H2O (a)	42.66	C
6.43	N	11.13	P2O5	35.10	NH3 (a)	13.53	18.71	H4P2O7 (a)	44.01	5.82	H2O (a)	42.46	"
6.42	N	11.12	P2O5	35.12	NH3 (a)	13.52	18.70	H4P2O7 (a)	44.03	5.83	H2O (a)	42.45	"
6.42	N	11.05	P2O5	34.62	NH3 (a)	13.44	18.28	H4P2O7 (a)	43.41	5.65	H2O (a)	43.15	"
----	N	10.86	P2O5	33.45	NH3 (a)	13.20	17.28	H4P2O7 (a)	41.94	5.25	H2O (a)	44.86	C + D
6.79	N	10.52	P2O5	31.82	NH3 (a)	12.79	15.87	H4P2O7 (a)	39.90	4.74	H2O (a)	47.31	D
7.02	N	9.79	P2O5	28.63	NH3 (a)	11.90	13.39	H4P2O7 (a)	35.90	3.86	H2O (a)	52.20	"
7.35	N	9.00	P2O5	24.86	NH3 (a)	10.94	11.10	H4P2O7 (a)	31.17	3.03	H2O (a)	57.89	"
7.95	N	8.53	P2O5	22.67	NH3 (a)	10.37	9.95	H4P2O7 (a)	28.42	2.61	H2O (a)	61.20	"
8.20	N	8.26	P2O5	21.27	NH3 (a)	10.04	9.32	H4P2O7 (a)	26.67	2.37	H2O (a)	63.29	"

Notes:
   Table 1  ^a  These values were calculated by the compiler.
   Table 2  ^b  The solid phases are: A=(NH₄)₂H₂P₂O₇; B=(NH₄)₃H₂P₂O₇·H₂O; C=(NH₄)₄P₂O₇; D=(NH₄)₄P₂O₇·H₂O.

Method/Apparatus/Procedure:
   The complexes, in capped glass tubes, were equilibrated in a cold room or in a water bath. The approach to equilibrium was followed by periodic petrographic and X-ray examination of the solid phases and by analyses of the liquid phase. Phosphorus was determined gravimetrically as quinolinium molybdophosphate¹ and nitrogen by distillation of ammonia with NaOH. pH was measured with a glass electrode. One-dimensional paper chromatography² was used to check the hydrolysis.

Source and Purity of Materials:
   The ammonium pyrophosphates and their solutions were prepared by ammoniation and vacuum evaporation of 0.3 NH₄P₂O₇ that had been prepared by ion exchange from solutions of recrystallized tetrasodium pyrophosphate. All operations were carried out at temperatures below 10 °C. No significant hydrolysis of the pyrophosphate was observed.

Estimated Errors:

   Temperature: The only information given is that the temperature was kept constant as follows: ±0.5 °C; 25 ± 0.02 °C.

References:
   ¹ C. H. Perrin, J. Assoc. Offic. Agr. Chemists 41, 758 (1958).
   ² E. Karl-Kroupa, Anal. Chem. 28, 1091 (1956).