IUPAC-NIST Solubilities Database

IUPAC-NIST Solubility Database
NIST Standard Reference Database 106

Solubility System: Potassium formate with Formic acid

Components:
   (1) Potassium formate; KCHO2; [590-29-4]  NIST Chemistry WebBook for detail
   (2) Formic acid; CH2O2; [64-18-6]  NIST Chemistry WebBook for detail

Original Measurements:
   Kendall, J.; Adler, H., J. Am. Chem. Soc. 43, 1470 (1921).

Variables:
   Temperature = -31.5 ºC to 167.5 ºC

Prepared By:
   T. A. Ageyeva

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

The solubility of potassium formate in formic acid.
t/°C	10⁰ * Mole Fraction₁	Solid Phase(s)^a
8.4	0.0	A
7.4	0.97	A
4.9	3.02	A
2.2	4.73	A
-0.9	6.36	A
-5.7	8.43	A
-12.6	10.74	A
-18.7	12.63	A
-23.8	13.88	A
-31.5	15.57	A
-29.0	16.32	B
-27.3	16.62	B
-23.5	17.44	B
-21.7	18.10	B
-19.5	18.88	B
-19.0	19.48	C
-16.0	19.91	C
-8.0	21.21	C
-0.6	22.79	C
-10.1	23.04	D
7.3	24.14	D
29.9	25.98	D
53.0	28.56	D
65.1	30.41	D
72.9	31.97	D
80.6	33.74	D
93.0	37.29	D
96.1	38.34	D
103.2	41.68	D
104.3	42.63	D
104.6	42.91	D
107.5	45.95	D
108.6	50.25	D
108.2	51.49	D
107.2	54.24	D
103.2	58.47	D
100.6	61.14	D
98.7	63.14	D
108.1	66.45	E
114.5	68.71	E
122.3	71.24	E
130.7	75.18	E
135.8	77.75	E
143.6	82.41	E
150.0	86.68	E
157.3	91.24	E
167.5	100.	E

Notes:
   ^a  The solid phases are: A = CH₂O₂; B = KCHO₂•3CH₂O₂; C = KCHO₂•2CH₂O₂; D = KCHO₂•CH₂O₂; E = KCHO₂.

Method/Apparatus/Procedure:
   The only information given is that the solubility values were determined by the freezing point method.

Source and Purity of Materials:
   The potassium salt was prepared by dissolving the carbonate in 90 % formic acid. After heating to drive out the CO₂, the salt was crystallized from solution and heated just below its melting point. It was then recrystallized from absolute ethanol and dried over 99% sulfuric acid in vacuo (m.p. = 440.7 K). The formic acid was prepared by treating a c.p. product with B₂O₃. It was then distilled in vacuo until a product melting above 281.6 K was obtained.

Estimated Errors:

   Temperature: Nothing is specified.