IUPAC-NIST Solubility Database
NIST Standard Reference Database 106

---

 Solubility System: Ammonium dihydrogenphosphate with Ammonium fluoride and Water

---

Components:
   (1) Ammonium dihydrogenphosphate; NH4H2PO4; [7722-76-1]  NIST Chemistry WebBook for detail
   (2) Ammonium fluoride; NH4F; [12125-01-8]  NIST Chemistry WebBook for detail
   (3) Water; H2O; [7732-18-5]  NIST Chemistry WebBook for detail

Original Measurements:
   Shilling, N.K.; Stetsova, G.S., Teknologiya Minerl'nykh Udobreniy (Leningrad) 68-71 (1977).

Variables:

   Concentration = Composition and temperature

Prepared By:
   L.V. Chernykh and J. Eysseltová

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

Solubility isotherms in the NH₄H₂PO₄-NH₄F-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	Solid Phase(s)(b)
-5	NH4H2PO4	13.2	1.40	NH4F	5	15	H2O	81.8	A
-5	NH4H2PO4	14.7	1.55	NH4F	3	9	H2O	82.3	A
-5	NH4H2PO4	17.5	2.38	NH4F	18.5	72.3	H2O	64	A
-5	NH4H2PO4	21	3.2	NH4F	21	90	H2O	58	A
-5	NH4H2PO4	14	2.5	NH4F	38	200	H2O	48	B
-5	NH4H2PO4	20.8	3.68	NH4F	30	150	H2O	49.2	B + C
0	NH4H2PO4	15.4	1.68	NH4F	5	1.7	H2O	79.6	A
0	NH4H2PO4	17.3	1.89	NH4F	3	1	H2O	79.7	A
0	NH4H2PO4	19.0	2.47	NH4F	14	5.6	H2O	67	A
0	NH4H2PO4	22	3.4	NH4F	21	9.9	H2O	57	A
0	NH4H2PO4	22.5	4.03	NH4F	29	16	H2O	48.5	A
0	NH4H2PO4	14	2.56	NH4F	38.5	21.9	H2O	47.5	B
5	NH4H2PO4	18.5	2.05	NH4F	3	1	H2O	78.5	A
5	NH4H2PO4	18.2	2.06	NH4F	5	2	H2O	76.8	A
5	NH4H2PO4	20	2.5	NH4F	11	4.3	H2O	69	A
5	NH4H2PO4	24	3.7	NH4F	20	9.6	H2O	56	A
5	NH4H2PO4	24	4.3	NH4F	28	16	H2O	48 (c)	A
5	NH4H2PO4	22.5	4.03	NH4F	29	16	H2O	48.5	A + B
5	NH4H2PO4	18.5	3.78	NH4F	39	25	H2O	42.5	B
10	NH4H2PO4	21.5	2.51	NH4F	4	1	H2O	74.5	A
10	NH4H2PO4	22	2.7	NH4F	6	2	H2O	72	A
10	NH4H2PO4	26	4.9	NH4F	28	16	H2O	46	A
10	NH4H2PO4	27	4.4	NH4F	20	10	H2O	53	A
10	NH4H2PO4	13	2.5	NH4F	41	24	H2O	46	B
10	NH4H2PO4	23	4.5	NH4F	33	20	H2O	44 (c)	B
20	NH4H2PO4	27	3.5	NH4F	5	2	H2O	68	A
20	NH4H2PO4	27	3.6	NH4F	8	3	H2O	65	A
20	NH4H2PO4	27	6.2	NH4F	35	25	H2O	38	A
20	NH4H2PO4	29	6.1	NH4F	30	20	H2O	41	A
20	NH4H2PO4	30	5.1	NH4F	19	10	H2O	51	A
20	NH4H2PO4	30	5.9	NH4F	26	16	H2O	44	A
20	NH4H2PO4	26	6.1	NH4F	37	27	H2O	37	A + B
30	NH4H2PO4	30	5.9	NH4F	26	16	H2O	44	A
30	NH4H2PO4	32	7.1	NH4F	29	20	H2O	39	A
30	NH4H2PO4	25	6.0	NH4F	39	29	H2O	36	B

Notes:
   Table 1  ^a  The molalitiese were calculated by the compilers based on 100w_i of the salts.
   Table 1  ^b  The solid phases are A=NH₄H₂PO₄; B=NH₄F; C=NH₄F·H₂O.
   Table 1  ^c  There are obvious misprints in these data (100w_i = 47 and 45, respectively) in the original article.

Method/Apparatus/Procedure:
   A polythermic method was used but no details are given. The nature of the solid phase was determined graphoanalytically (no details are given) and checked by IR spectroscopy.

Source and Purity of Materials:
   Chemically pure NH₄H₂PO₄ and NH₄F were used.

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

---

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)