NIST-IUPAC Solubility Data Series

Potassium formate with Cobalt formate and Water (IUPAC SDS Volume 73)

SDS Volume

Volume 73. Metal and Ammonium Formate Systems, p None

Source Publication

Portnova, S. M.; Petrova, E. V.; Lyashchenko, A. K.; Lepeshkov, I. N.; Zh. Neorg. Khim. 28, 2952-7 (1983).

Conditions:

Room Temp: Composition at 25 °C

Compilers:

St. Trendafilova, Chr. Balarew

Methodology:

The isothermal method was used. Equilibrium was reached in 4 weeks. The potassium content of both phases was determined by the tetraphenylborate method [1].The cobalt content was determined complexometrically by back titration with $\ce{ZnSO4}$ using Xylenol Orange in a urotropin medium as indicator.

Sample Information:

$\ce{Co(CHO2)2.2H2O}$ was prepared from PA reagent grade cobalt nitrate by adding a $\ce{KOH}$ soln. and then dissolving the $\ce{Co(OH)2}$ in a formic acid soln. $\ce{KCHO2}$ was prepared by neutralizing a 85% formic acid soln. with dilute $\ce{KOH}$. After crystallization the crystals were washed with ethanol and dried over $\ce{H2SO4}$.

Measurement Errors:

Mass concentration (m/v) (1): It is very strange to have supersaturated solution in equilibrium with the same crystal phases as these existing in equilibrium with the saturated solution.

Methodology Citation

¹ Pribil, R.; Maricova, D.; Chem. Listy 46, 542 (1952).

System Components:

Potassium formate, $\ce{ KCHO2 }$; [590-29-4] NIST WebBook
Cobalt formate, $\ce{ Co(CHO2)2 }$; [544-18-3] NIST WebBook
Water, $\ce{ H2O }$; [7732-18-5] NIST WebBook

Experimental Data

These same data, expressed as mol %, are published in: E. V. Petrova, A. K. Lyashchenko, A. F. Borina, and S. M. Portnova, Zh. Neorg. Khim. 28, 3158-63 (1983).

100w₁	100w₂	m₁ (mol/kg) ^b	m₂ (mol/kg) ^b	Phase (s) () ^a
-	2.42	-	0.166	A
1.76	1.59	0.216	0.110	A
11.53	0.51	1.558	0.039	A
15.64	0.46	2.216	0.037	A
23.28	0.48	3.630	0.042	A
33.86	0.68	6.149	0.069	A
33.66	1.11	7.003	0.119	A + B
37.35	1.49	7.260	0.163	B
40.06	1.59	8.162	0.183	B
46.78	1.67	10.79	0.217	B
55.12	1.11	14.97	0.170	B
57.49	0.99	16.46	0.16	B
63.36	0.71	20.96	0.13	B + C
74.48	0.02	34.75	0.01	C
81.82	-	53.503	-	C
43.64	1.82	9.512	0.224	A
43.47	2.10	9.494	0.259	A + B
53.12	1.90	14.04	0.284	B
64.39	1.21	22.25	0.236	B
71.21	0.86	30.31	0.21	B
73.73	0.71	34.29	0.18	B
76.33	0.46	39.10	0.13	B + C
78.33	0.16	43.29	0.049	C
80.38	0.14	49.05	0.048	C