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:
   Iovi, A.; Haiduc, C., Rev. Roum. Chim. 16, 1743 (1971).

Variables:

   Concentration = Temperaure. Equimolar mixtures of KCl + NH₄H₂PO₄ or NH₄Cl and KH₂PO₄ are used.

Prepared By:
   J. Eysseltová

Experimental Data:   (Notes on the Nomenclature)
  

Molar Solubilty in equimolar mixtures in the K⁺, NH₄⁺ || Cl^–, H₂PO₄^– -H₂O system

Solution number	t/°C	Chemical1	Solubility1	Chemical2	Solubility2	Chemical3	Solubility3	Chemical4	Solubility4	ρ [g/cm3]	Comment(s)
1	20	H2PO4-	0.60	Cl-	4.77	K+	2.18	NH4+	3.19	1.1585	(A) KCl + NH4H2PO4
2	25	H2PO4-	0.70	Cl-	4.76	K+	2.18	NH4+	3.28	1.1640	(A) KCl + NH4H2PO4
3	40	H2PO4-	1.00	Cl-	4.49	K+	2.31	NH4+	3.18	1.1690	(A) KCl + NH4H2PO4
4	60	H2PO4-	1.50	Cl-	4.36	K+	2.44	NH4+	3.42	1.1880	(A) KCl + NH4H2PO4
5	75	H2PO4-	2.20	Cl-	4.36	K+	2.82	NH4+	3.74	1.2360	(A) KCl + NH4H2PO4
6	80	H2PO4-	2.50	Cl-	4.23	K+	2.95	NH4+	3.78	1.2479	(A) KCl + NH4H2PO4
1	20	H2PO4-	0.60	Cl-	4.77	K+	2.18	NH4+	3.19	1.1585	(B) NH4Cl + KH2PO4
2	25	H2PO4-	0.70	Cl-	4.72	K+	2.18	NH4+	3.24	1.1640	(B) NH4Cl + KH2PO4
3	40	H2PO4-	1.00	Cl-	4.39	K+	2.31	NH4+	3.08	1.1690	(B) NH4Cl + KH2PO4
4	60	H2PO4-	1.50	Cl-	4.36	K+	2.44	NH4+	3.42	1.1880	(B) NH4Cl + KH2PO4
5	75	H2PO4-	2.20	Cl-	4.26	K+	2.82	NH4+	3.64	1.2360	(B) NH4Cl + KH2PO4
6	80	H2PO4-	2.50	Cl-	4.22	K+	2.95	NH4+	3.77	1.2479	(B) NH4Cl + KH2PO4

The  compiler has recalculated these values as follows:

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
1(A,B)	H2PO4-	5.02	0.76	Chloride	14.60	6.04	potassium	7.35	2.76	H2PO4-	4.95	4.03
2(A)	H2PO4-	5.83	0.89	Chloride	14.50	6.07	potassium	7.32	2.78	H2PO4-	5.07	4.18
2(B)	H2PO4-	5.83	0.89	Chloride	14.38	6.01	potassium	7.32	2.77	H2PO4-	5.01	4.11
3(A)	H2PO4-	8.29	1.30	Chloride	13.62	5.86	potassium	7.72	3.01	H2PO4-	4.89	4.14
3(B)	H2PO4-	8.29	1.29	Chloride	13.32	5.69	potassium	7.72	2.99	H2PO4-	4.74	3.99
4(A,B)	H2PO4-	12.24	2.05	Chloride	13.01	5.96	potassium	8.03	3.33	H2PO4-	5.18	4.67
5(A)	H2PO4-	17.26	3.18	Chloride	12.51	6.31	potassium	8.92	4.08	H2PO4-	5.44	5.40
5(B)	H2PO4-	17.26	3.16	Chloride	12.22	6.12	potassium	8.92	4.05	H2PO4-	6.30	5.22
6(A)	H2PO4-	19.43	3.72	Chloride	12.02	6.29	potassium	9.24	4.39	H2PO4-	5.45	5.61
6(B)	H2PO4-	19.43	3.71	Chloride	11.99	6.27	potassium	9.24	4.38	H2PO4-	5.43	5.59

Molar solubility in equimolar mixtures in the K⁺, NH₄⁺ || Cl^–, H₂PO₄^– - H₂O system. THe following concentrations are expressed as mol/100 mol of solute.

Solution number	Chemical1	Solubility1	Chemical2	Solubility2	Chemical3	Solubility3	Chemical4	Solubility4	Chemical5	Solubility5
1(A,B)	H2PO4-	11.17	chloride	88.83	potassium	40.64	ammonium	59.36	water	818
2(A)	H2PO4-	12.78	chloride	87.22	potassium	39.94	ammonium	60.06	water	798
2(B)	H2PO4-	12.89	chloride	87.19	potassium	40.26	ammonium	59.74	water	807
3(A)	H2PO4-	18.15	chloride	81.85	potassium	42.83	ammonium	57.17	water	804
3(B)	H2PO4-	18.48	chloride	81.52	potassium	42.78	ammonium	57.22	water	796
4(A,B)	H2PO4-	25.59	chloride	74.41	potassium	41.62	ammonium	58.38	water	694
5(A)	H2PO4-	33.50	chloride	66.50	potassium	41.03	ammonium	56.97	water	586
5(B)	H2PO4-	34.05	chloride	65.95	potassium	43.68	ammonium	56.32	water	599
6(A)	H2PO4-	37.16	chloride	62.84	potassium	43.90	ammonium	56.10	water	556
6(B)	H2PO4-	37.17	chloride	62.83	potassium	43.93	ammonium	56.07	water	557

Method/Apparatus/Procedure:
   The samples were equilibrated by stirring for 10 hrs in a thermostat. The potassium content was determined with the use of a type C Zeiss Jena Model III flame photometer and gravimetrically as KClO₄, phosphate ion was determined by a compleximetric titration with MgCl₂ using Eriochrome Black T as indicator,¹ chloride was determined by potentiometric titration with AgNO₃, and NH₃ was determined by the Kjeldahl method.

Source and Purity of Materials:
   No information is given.

Estimated Errors:
   Solubility: No information is given.
   Temperature: No information is given.

References:
   ¹C. Liteanu, Chimie anilitica Cantitativa, Ed. didactica si pedagogica, Bucuresti, p. 508 (1964).

---

Distributed by the Office of Data and Informatics of the National Institute of Standards and Technology (NIST) Material Measurement Laboratory (MML).
Website is owned by NIST (an agency of the U.S. Department of Commerce)

---

Last updated: February 18, 2015 (Created: August 17, 2007)