IUPAC-NIST Solubilities Database

IUPAC-NIST Solubility Database
NIST Standard Reference Database 106

Solubility System: Potassium formate with Potassium tetraborate and Water

Components:
   (1) Potassium formate; KCHO2; [590-29-4]  NIST Chemistry WebBook for detail
   (2) Potassium tetraborate; K2B4O7; [1332-77-0]  NIST Chemistry WebBook for detail
   (3) Water; H2O; [7732-18-5]  NIST Chemistry WebBook for detail

Original Measurements:
   Berniyazova, D.G.; Kalacheva, V.G.; Schwartz, E.M., Zh. Neorg. Khim. 31, 1045-8 (1986).

Variables:

   Concentration = Composition at 15 ºC

Prepared By:
   St. Tepavitcharova and St. Trendafilova

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

Solubility values in the KCHO₂-K₂B₄O₇-H₂O system at 15 °C.
Chemical₁	Phase	Mass Fraction w₁	m₁ [mol kg-1]^a	Chemical₂	Mass Fraction w₂	m₂ [mol kg-1]^a	Solid Phase(s)^b
K2B4O7	Liquid	8.74	0.41	KCHO2	----	----	A
K2B4O7	Liquid	8.94	0.48	KCHO2	10.82	1.60	A
K2B4O7	Liquid	7.52	0.45	KCHO2	20.43	3.37	A
K2B4O7	Liquid	7.48	0.46	KCHO2	22.18	3.75	A
K2B4O7	Liquid	6.66	0.43	KCHO2	26.48	4.71	A
K2B4O7	Liquid	6.58	0.43	KCHO2	27.93	5.07	A
K2B4O7	Liquid	6.02	0.39	KCHO2	28.16	5.09	A
K2B4O7	Liquid	5.49	0.35	KCHO2	28.24	5.07	A
K2B4O7	Liquid	5.14	0.34	KCHO2	30.42	5.61	A
K2B4O7	Liquid	4.98	0.34	KCHO2	32.84	6.28	A
K2B4O7	Liquid	4.63	0.34	KCHO2	36.23	7.28	A
K2B4O7	Liquid	4.27	0.33	KCHO2	39.56	8.37	A
K2B4O7	Liquid	3.42	0.27	KCHO2	42.42	9.31	A
K2B4O7	Liquid	2.68	0.23	KCHO2	46.61	10.93	A
K2B4O7	Liquid	1.25	0.11	KCHO2	49.89	12.14	A+B
K2B4O7	Liquid	0.69	0.06	KCHO2	49.56	11.84	B
K2B4O7	Liquid	0.22	0.02	KCHO2	49.69	11.79	B
K2B4O7	Liquid	----	----	KCHO2	49.09	11.46	B

Notes:
   ^a  These values were calculated by the compilers.
   ^b  The solid phases are: A = K₂B₄O₇•4H₂O; B = KCHO₂.

Method/Apparatus/Procedure:
   The isothermal method was used. Equilibrium was achieved within 6 h. The K⁺ content was determined by the cobaltousnitrous method. The boron concentration was determined by titration with alkali using mannitol, after the sample had been evaporated to dryness, ignited at 600 °C and dissolved in boiling HCl.¹ The formate content was determined from the carbon content by ignition. The composition of the solid phases was determined by the Schreinemakers' method.

Source and Purity of Materials:
   Suprapure grade K₂ B₄O₇ was used. The KCHO₂ was prepared according to the directions given in Mentzen.²

Estimated Errors:
   Solubility: The determined solubilities of KCHO₂ are too low.

References:
   ¹Yu. N. Knipovich and Yu. V. Morachevskii, Analysis of Mineral Ores, 3rd ed., (L.Gostechizdat, p. 281, 1959).
   ²B. F. Mentzen, Inorg. Chim. Acta 43, 237 (1980).