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:
   Uno, S., Kogyo Kagaku Zashi 1940, 43, 399; J. Soc. Chim. Ind., Japan, Suppl. Binding 1940, 43, 168B/70B.

Variables:

   Concentration = Composition at 25 ºC and 70 ºC

Prepared By:
   J. Eysseltová and Hiroshi Miyamoto

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

Composition of the saturated solutions.^a
t/°C	Chemical₁	Composition₁ [g/100g H2O]	Chemical₂	Composition₂ [g/100g H2O]	Chemical₃	10² * Mass Fraction w₃^(b)	m₃ [mol/kg]^(b)	Chemical₄	10² * Mass Fraction w₄^(b)	m₄ [mol/kg]^(b)	Chemical₅	10² * Mass Fraction w₅^(b)
25	NH4H2PO4	40.7	H3PO4	0	NH3	4.28	3.54	H3PO4	24.6	3.54	H2O	71.1
25	NH4H2PO4	51.9	H3PO4	20.5	NH3	4.46	4.51	H3PO4	37.5	6.60	H2O	58.0
25	NH4H2PO4	66.6	H3PO4	48.9	NH3	4.58	5.79	H3PO4	49.0	10.8	H2O	46.4
25	NH4H2PO4	87.3	H3PO4	90.6	NH3	4.65	7.59	H3PO4	59.4	16.8	H2O	36.0
25	NH4H2PO4	102.2	H3PO4	119.3	NH3	4.706	8.884	H3PO4	64.19	21.06	H2O	31.10
25	NH4H2PO4	130.7	H3PO4	169.3	NH3	4.837	11.36	H3PO4	70.16	28.64	H2O	25.00
25	NH4H2PO4	239.0	H3PO4	336.5	NH3	5.238	20.78	H3PO4	79.96	55.11	H2O	14.80
70	NH4H2PO4	100.7	H3PO4	0	NH3	7.428	8.753	H3PO4	42.74	8.753	H2O	49.83
70	NH4H2PO4	105.7	H3PO4	14.10	NH3	7.119	9.188	H3PO4	47.38	10.63	H2O	45.50
70	NH4H2PO4	110.7	H3PO4	23.80	NH3	6.988	9.623	H3PO4	50.36	12.05	H2O	42.64
70	NH4H2PO4	136.1	H3PO4	61.60	NH3	6.768	11.83	H3PO4	59.64	18.12	H2O	33.59
70	NH4H2PO4	157.1	H3PO4	96.50	NH3	6.577	13.66	H3PO4	65.14	23.50	H2O	28.28
70	NH4H2PO4	249.9	H3PO4	206.5	NH3	6.649	21.72	H3PO4	75.37	42.79	H2O	17.97

Notes:
   Table 1  ^a  The source of the solid phase was not repeated.
   Table 1  ^b  These values were calculated by the compilers.

Method/Apparatus/Procedure:
   The isothermal method was used. Ammonium dihydrogenphosphate, phosphoric acid and water were placed in ampules. The mixtures were shaken in a thermostat at 25 °C and 70 °C. After equilibrium was established, the mixtures were allowed to settle. A pipet was used in sampling aliquots of the saturated solution for analysis.

Source and Purity of Materials:
   Chemically pure reagents were used. Ammonium dihydrogenphosphate was recrystallized.

Estimated Errors:
   Solubility: nothing specified.
   Temperature: precision ±0.05 K at 298 K and ±0.5 K at 343 K.