IUPAC-NIST Solubilities Database

IUPAC-NIST Solubility Database
NIST Standard Reference Database 106

Solubility System: Ammonium dihydrogenphosphate with Ammonium chloride, Potassium dihydrogenphosphate, Potassium chloride and Water

Components:
   (1) Ammonium chloride; NH4Cl; [12125-02-9]  NIST Chemistry WebBook for detail
   (2) Ammonium dihydrogenphosphate; NH4H2PO4; [7722-76-1]  NIST Chemistry WebBook for detail
   (3) Potassium chloride; KCl; [7747-40-7]  NIST Chemistry WebBook for detail
   (4) Potassium dihydrogenphosphate; KH2PO4; [7778-77-0]  NIST Chemistry WebBook for detail
   (5) Water; H2O; [7732-18-5]  NIST Chemistry WebBook for detail

Original Measurements:
   Askenasy, P.; Nessler, F., F.Z. Anorg. Chem. 189, 305 (1930).

Variables:

   Concentration = Composition at 0 ºC.

Prepared By:
   J. Eysseltová

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

Part 1. The authors’ data: Points of simultaneous crystallization of several solid phases in the K⁺, NH₄⁺ || Cl^–, H₂PO₄^– - H₂O system at 0 °C.
Solution number	Chemical₁	10² * Mole Fraction₁	Chemical₂	10² * Mole Fraction₂	Chemical₃	10² * Mole Fraction₃	Chemical₄	10² * Mole Fraction₄	Chemical₅	10² * Mole Fractio₅n	Solid Phase(s)^(a)	ρ [g/cm3]
1	H2PO4-	7.6	Cl-	92.4	K+	8.0	NH4+	92.0	H2O	925	"NH4Cl" + "NH4H2PO4"	1.1100
2	H2PO4-	7.7	Cl-	92.3	K+	12.1	NH4+	87.9	H2O	905	"NH4Cl" + "NH4H2PO4"	1.1134
3	H2PO4-	8.1	Cl-	91.9	K+	17.9	NH4+	82.1	H2O	888	"NH4Cl" + "NH4H2PO4"	1.1300
4	H2PO4-	8.5	Cl-	91.5	K+	24.4	NH4+	75.6	H2O	850	"NH4Cl" + "NH4H2PO4"	1.1335
5	H2PO4-	8.7	Cl-	91.3	K+	28.7	NH4+	71.3	H2O	810	ternary eutectic point	1.1385
6	H2PO4-	8.3	Cl-	91.7	K+	29.8	NH4+	70.2	H2O	865	"KCl" + "KH2PO4"	1.1504
7	H2PO4-	8.3	Cl-	91.7	K+	32.7	NH4+	67.3	H2O	887	"KCl" + "KH2PO4"	1.1514
8	H2PO4-	7.5	Cl-	92.5	K+	66.6	NH4+	33.4	H2O	1135	"KCl" + "KH2PO4"	1.1657
9	H2PO4-	7.7	Cl-	92.3	K+	85.8	NH4+	14.2	H2O	1310	"KCl" + "KH2PO4"	1.1695
10	H2PO4-	7.3	Cl-	92.7	K+	90.0	NH4+	10.0	H2O	1380	"KCl" + "KH2PO4"	1.1740
11	H2PO4-	3.6	Cl-	96.4	K+	28.2	NH4+	71.8	H2O	845	"KCl" + "NH4Cl"	1.1272

Distribution of K⁺ and NH₄⁺ in the solid and liquid phases of the solutions existing in equilibrium with (K₂NH₄)H₂PO₄.
Solution number	Chemical₁	10² * Mole Fraction₁	Chemical₂	10² * Mole Fraction₂	Chemical₃	10² * Mole Fraction₃	Chemical₄	10² * Mole Fraction₄	Chemical₅	10² * Mole Fractio₅n	Chemical₆	Mole Fraction₆	Mole Fraction₇
12	H2PO4-	9.8	Cl-	90.2	K+	57.8	NH4+	42.2	H2O	1090	K+	85.5	14.5
13	H2PO4-	45.9	Cl-	54.1	K+	49.2	NH4+	50.8	H2O	1690	K+	78.9	21.1
14	H2PO4-	33.8	Cl-	66.2	K+	45.5	NH4+	54.5	H2O	1680	K+	71.7	28.3
15	H2PO4-	27.4	Cl-	72.6	K+	42.7	NH4+	57.3	H2O	1450	K+	66.1	33.9
16	H2PO4-	27.2	Cl-	72.8	K+	43.3	NH4+	56.7	H2O	1565	K+	64.8	35.2
17	H2PO4-	19.7	Cl-	80.3	K+	40.9	NH4+	59.1	H2O	1135	K+	62.2	37.8
18	H2PO4-	13.1	Cl-	86.9	K+	38.9	NH4+	61.1	H2O	1130	K+	62.2	37.8
19	H2PO4-	26.7	Cl-	73.3	K+	44.2	NH4+	55.8	H2O	1555	K+	56.4	45.6
20	H2PO4-	24.5	Cl-	75.5	K+	36.9	NH4+	63.1	H2O	1665	K+	55.7	44.3
21	H2PO4-	9.8	Cl-	90.2	K+	26.6	NH4+	73.4	H2O	925	K+	31.2	68.8
22	H2PO4-	18.3	Cl-	81.7	K+	28.7	NH4+	71.3	H2O	1235	K+	29.2	70.8

Part 2. The compiler has recalculated the authors’ data to give the following values.
Solution number	Chemical₁	10² * Mass Fraction w₁	m₁	Chemical₂	10² * Mass Fraction w₂	m₂	Chemical₃	10² * Mass Fraction w₃	m₃	Chemical₄	10² * Mass Fraction w₄	m₄	Chemical₅	10² * Mass Fraction w₅	Solid Phase(s)^(a)
1	H2PO4-	3.25	0.45	Cl-	14.47	554	K+	1.38	0.48	NH4+	7.32	5.52	H2O	73.55	A + B
2	H2PO4-	3.33	0.47	Cl-	14.63	566	K+	2.11	0.74	NH4+	7.08	5.39	H2O	72.82	A + B
3	H2PO4-	3.53	0.50	Cl-	14.67	574	K+	3.15	1.11	NH4+	6.66	5.13	H2O	71.96	A + B
4	H2PO4-	3.80	0.55	Cl-	14.96	598	K+	4.39	1.59	NH4+	6.28	4.94	H2O	70.54	A + B
5	H2PO4-	4.00	0.59	Cl-	15.36	626	K+	5.32	1.96	NH4+	6.10	4.89	H2O	69.19	C
6	H2PO4-	3.64	0.53	Cl-	14.74	588	K+	5.28	1.91	NH4+	5.73	4.50	H2O	70.58	D + E
7	H2PO4-	3.57	0.51	Cl-	14.44	574	K+	5.67	2.04	NH4+	5.39	4.21	H2O	70.91	D + E
8	H2PO4-	2.63	0.36	Cl-	11.86	452	K+	9.41	3.25	NH4+	2.17	1.63	H2O	73.90	D + E
9	H2PO4-	2.39	0.32	Cl-	10.48	391	K+	10.74	3.63	NH4+	0.82	0.60	H2O	75.54	D + E
10	H2PO4-	2.17	0.29	Cl-	10.10	373	K+	10.81	3.62	NH4+	0.55	0.40	H2O	76.34	D + E
11	H2PO4-	1.63	0.23	Cl-	15.99	633	K+	5.15	1.85	NH4+	6.05	4.72	H2O	71.15	D + F
12	H2PO4-	3.54	0.49	Cl-	11.94	459	K+	8.43	2.94	NH4+	2.84	2.15	H2O	73.23	G
13	H2PO4-	11.23	1.50	Cl-	4.84	177	K+	4.85	1.61	NH4+	2.31	1.66	H2O	76.65	G
14	H2PO4-	8.48	1.11	Cl-	6.07	218	K+	4.60	1.50	NH4+	2.54	1.80	H2O	78.28	G
15	H2PO4-	7.80	1.04	Cl-	7.56	278	K+	4.90	1.63	NH4+	3.03	2.19	H2O	76.68	G
16	H2PO4-	7.30	0.96	Cl-	7.15	258	K+	4.68	1.53	NH4+	2.83	2.01	H2O	78.02	G
17	H2PO4-	6.86	0.96	Cl-	10.22	393	K+	5.74	2.00	NH4+	3.82	2.89	H2O	73.34	G
18	H2PO4-	4.65	0.64	Cl-	11.28	427	K+	5.56	1.91	NH4+	4.03	3.00	H2O	74.46	G
19	H2PO4-	7.21	0.95	Cl-	7.23	261	K+	4.81	1.57	NH4+	2.80	1.99	H2O	77.93	G
20	H2PO4-	6.31	0.81	Cl-	7.12	251	K+	3.83	1.23	NH4+	3.02	2.10	H2O	79.69	G
21	H2PO4-	4.10	0.58	Cl-	13.81	541	K+	4.49	1.59	NH4+	5.71	4.40	H2O	71.88	G
22	H2PO4-	6.05	0.82	Cl-	9.88	367	K+	3.82	1.29	NH4+	4.38	3.20	H2O	75.84	G

Notes:
   Table 1  ^a  A formula in quotation marks refers to a solid solution rich in that component.
   Table 2  ^a  The solid phases are: a="NH₄Cl" B="NH₄H₂PO₄"; C=ternary eutectic point; D="KCl"; E="KH₂PO₄"; F="NH₄Cl"; G=a precipitate designated as (K,NH₄)H₂PO₄. The quotation marks have the same meaning as on the preceding page.

Method/Apparatus/Procedure:
   Binary eutonic solutions were prepared on the basis of a preliminary investigation of the boundary ternary systems. Samples on the curve for the simultaneous crystallization of two salts were then prepared by adding a third component. The mixtures were shaken in a thermostat for 2 to 4 days. The solid phase was isolated by centrifuging. The analytical methods are not described.

Source and Purity of Materials:
   No information is given.

Estimated Errors:
   Solubility: No information given.
   Temperature: The temperature was controlled to within ± 0.1 K. No other information is given.