Components:
(1) Potassium formate,
KCHO2; [590-29-4]
NIST WebBook
(2) Potassium tetraborate,
K2B4O7; [1332-77-0]
NIST WebBook
(3) Water,
H2O; [7732-18-5]
NIST WebBook
Original Measurements
Berniyazova, D. G.; Kalacheva, V. G.; Schwartz, E. M.; Zh. Neorg. Khim. 31, 1045-8 (1986).
Variables:
Ambient temperature: Composition at 15 °C
Prepared by:
St. Trendafilova, St. Tepavitcharova
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:
Mass concentration (m/v) (1): The determined solubilities of KCHO2 are too low.
References
1
Knipovich, Yu. N.; Morachevskii, Yu. V.; Analysis of Mineral Ores, 3rd ed., (L. Gostechizdat, p. 281, 1959).
2
Mentzen, B. F.; Oddon, Y.; Inorg. Chim. Acta 43, 237 (1980).
Experimental Values:
Solubility values in the KCHO2-K2B4O7-H2O system at 15°C.
| 100w2 | 100w1 | m1 (mol/kg)a | m2 (mol/kg)a | Phase (s)b |
|---|---|---|---|---|
| 8.74 | - | 4.1 x 10-1 | - | A |
| 8.94 | 10.82 | 4.8 x 10-1 | 1.6 | A |
| 7.52 | 20.43 | 4.5 x 10-1 | 3.37 | A |
| 7.48 | 22.18 | 4.6 x 10-1 | 3.75 | A |
| 6.66 | 26.48 | 4.3 x 10-1 | 4.71 | A |
| 6.58 | 27.93 | 4.3 x 10-1 | 5.07 | A |
| 6.02 | 28.16 | 3.9 x 10-1 | 5.09 | A |
| 5.49 | 28.24 | 3.5 x 10-1 | 5.07 | A |
| 5.14 | 30.42 | 3.4 x 10-1 | 5.61 | A |
| 4.98 | 32.84 | 3.4 x 10-1 | 6.28 | A |
| 4.63 | 36.23 | 3.4 x 10-1 | 7.28 | A |
| 4.27 | 39.56 | 3.3 x 10-1 | 8.37 | A |
| 3.42 | 42.42 | 2.7 x 10-1 | 9.31 | A |
| 2.68 | 46.61 | 2.3 x 10-1 | 10.93 | A |
| 1.25 | 49.89 | 1.1 x 10-1 | 12.14 | A + B |
| 6.9 x 10-1 | 49.56 | 6 x 10-2 | 11.84 | B |
| 2.2 x 10-1 | 49.69 | 2 x 10-2 | 11.79 | B |
| - | 49.09 | - | 11.46 | B |
(a) These values were calculated by the compilers. (b) The solid phases are: A = K2B4O7ยท4H2O; B = KCHO2.
