IUPAC-NIST Solubilities Database

IUPAC-NIST Solubility Database
NIST Standard Reference Database 106

Solubility System: Potassium formate with Calcium formate and Water

Components:
   (1) Potassium formate; KCHO2; [590-29-4]  NIST Chemistry WebBook for detail
   (2) Calcium formate; Ca(CHO2)2; [544-17-2]  NIST Chemistry WebBook for detail
   (3) Water; H2O; [7732-18-5]  NIST Chemistry WebBook for detail

Original Measurements:
   Portnova, S.M.; Palitskaya, T.A., Zh. Neorg. Khim. 39,163-168 (1994).

Variables:

   Concentration = Composition at 25 ºC

Prepared By:
   Chr. Balarew and St. Trendafilova

Experimental Remarks:

   The molality values were calculated by the compilers.

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

Solubility values in the KCHO₂-Ca(CHO₂)₂-H₂O system at 25 °C.
Chemical₁	Phase	Mass Fraction w₁	m₁ [mol kg-1]	Chemical₂	Mass Fraction w₂	m₂ [mol kg-1]	Solid Phase(s)^a
Ca(CHO2)2	Liquid	14.43	1.296	KCHO2	---	---	À
Ca(CHO2)2	Liquid	6.44	6.384	KCHO2	16.04	2.460	A
Ca(CHO2)2	Liquid	3.94	4.269	KCHO2	25.14	4.214	A
Ca(CHO2)2	Liquid	2.74	3.408	KCHO2	35.48	6.827	A
Ca(CHO2)2	Liquid	5.26	1.159	KCHO2	59.88	20.420	A
Ca(CHO2)2	Liquid	3.08	6.276	KCHO2	59.21	18.666	A
Ca(CHO2)2	Liquid	6.31	1.392	KCHO2	58.86	20.089	A
Ca(CHO2)2	Liquid	6.30	1.405	KCHO2	59.35	20.480	A
Ca(CHO2)2	Liquid	6.55	1.507	KCHO2	60.07	21.393	A
Ca(CHO2)2	Liquid	6.61	1.528	KCHO2	60.15	21.512	A+B
Ca(CHO2)2	Liquid	6.15	1.463	KCHO2	61.56	22.664	B
Ca(CHO2)2	Liquid	4.46	1.022	KCHO2	62.03	22.005	B
Ca(CHO2)2	Liquid	4.33	1.008	KCHO2	63.01	22.705	B
Ca(CHO2)2	Liquid	2.08	5.089	KCHO2	66.51	25.173	B
Ca(CHO2)2	Liquid	1.42	3.424	KCHO2	66.71	24.883	B+C
Ca(CHO2)2	Liquid	0.41	1.185	KCHO2	73.00	32.627	B+C
Ca(CHO2)2	Liquid	0.18	6.506	KCHO2	78.56	43.929	B+C
Ca(CHO2)2	Liquid	0.17	6.302	KCHO2	79.10	45.361	C
Ca(CHO2)2	Liquid	---	---	KCHO2	81.82	53.503	C

Notes:
   ^a  The solid phases are À= Ca(CHO₂)₂ , B= K₄Ca(CHO₂)₆, C= KCHO₂ .

Method/Apparatus/Procedure:
   The isothermal solubility method was used. Four weeks were allowed for the attainment of equilibrium at a constant temperature. The composition of the liquid and wet solid phases was determined as follows.The K⁺ content was determined by the tetraphenylborate method and gravimetrically. Ca²⁺ was determined complexometrically in a basic medium, using methylthymolblue as indicator. The composition of the solid phases was determined by elemental analysis, thermogravimetrically, crystallo-optically and by x-ray diffraction. The composition of the suction dried solid phase was also determined by the Schreinemakers' method.

Source and Purity of Materials:
   KCHO₂ was obtained by the reaction of KOH and p.a. grade H₂CO₂¹. Ca(CHO₂)₂ was obtained by the reaction of Ca(OH) ₂"pure" grade and H₂CO₂.

Estimated Errors:

References:
   ¹L. S. Itkina, N. M. Chaplygina, and E. V. Petrova, Zh. Neorg. Khim. 24, 788 (1979).