Components:
(1) Cobalt formate,
Co(CHO2)2; [544-18-3]
NIST WebBook
(2) Water,
H2O; [7732-18-5]
NIST WebBook
Original Measurements
Stoilova, D.; Balarew, C.; Vassileva, V.; Russeva, St.; Zh. Neorg. Khim. 26, 1641 (1981).
Variables:
Ambient temperature: 10 - 80 °C
Prepared by:
St. Trendafilova, Chr. Balarew
Method/Apparatus/Procedure:
The decrease of supersaturation was studied isothermally in about a 2% excess of formic acid to suppress hydrolysis of the salt. Equilibrium was reached in 15-20 h. The cobalt concentration was determined using Complexone III at pH 5.5-6 with Xylenol orange as indicator. The composition of the solid phase was determined by x-ray diffraction and chemical analysis.
Source and Purity of Materials:
- Cobalt formate was prepared by neutralizing basic cobalt carbonate with dilute formic acid.
Experimental Values:
Solubility polytherm of the Co(CHO2)2-H2O system.
| T (°C) | 100w1 | m1 (mol/kg)a | Phase (s)b |
|---|---|---|---|
| 10.0 | 2.03 | 1.39 x 10-1 | A |
| 15.0 | 2.18 | 1.50 x 10-1 | A |
| 20.0 | 2.34 | 1.61 x 10-1 | A |
| 25.0 | 2.44 | 1.68 x 10-1 | A |
| 30.0 | 2.55 | 1.76 x 10-1 | A |
| 35.0 | 2.69 | 1.86 x 10-1 | A |
| 40.0 | 2.85 | 1.97 x 10-1 | A |
| 45.0 | 3.05 | 2.11 x 10-1 | A |
| 50.0 | 3.33 | 2.31 x 10-1 | A |
| 55.0 | 3.41 | 2.37 x 10-1 | A |
| 60.0 | 3.59 | 2.50 x 10-1 | A |
| 65.0 | 3.79 | 2.64 x 10-1 | A |
| 70.0 | 4.02 | 2.81 x 10-1 | A |
| 75.0 | 4.19 | 2.94 x 10-1 | A |
| 80.0 | 4.28 | 3.00 x 10-1 | A |
(a) These values were calculated by the compilers. (b) The solid phase is: A = Co(CHO2)2ยท2H2O.
