Components:
(1) Copper formate,
Cu(CHO2)2; [544-19-4]
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(2) Ammonium formate,
NH4CHO2; [540-69-2]
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(3) Formic acid,
CH2O2; [64-18-6]
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Original Measurements
Davidson, A. W.; Holm, V.; J. Am. Chem. Soc. 53, 1350 (1931).
Variables:
Ambient temperature: 31 - 77 °C
Prepared by:
Method/Apparatus/Procedure:
The solubility values were measured by the freezing point method.1 Samples of solid phase were prepared for analysis by crystallizing from solution, filtering and drying between porous tiles. A quantitative determination of copper by the electrolytic method was sufficient to fix the composition of the compound.
Source and Purity of Materials:
- The copper salt was prepared by dissolving the basic carbonate in 50% formic acid, heating to expel CO2, cooling to precipitate out the crystals, pressing the crystals between porous tiles and drying them at 348 K for 10 h. The ammonium formate was prepared by passing dry NH3 into 100% formic acid and drying the product over 99% sulfuric acid; melting point = 390-391 K. Formic acid was prepared by treating the 90% acid with B2O3; melting point = 281.4-281.7 K.
Estimated Errors:
Ambient temperature: ±0.5 K
Mass concentration (m/v) (1): No information is given.
References
1 Davidson, A. W.; McAllister, W. H.; J. Am. Chem. Soc. 52, 507 (1930).
Experimental Values:
Solubility in the Cu(CHO2)2-NH4CHO2-CH2O2 system.
| T (°C) | R2/(2+3)R | 100x1 | Phase (s) |
|---|---|---|---|
| 65.0 | 1 x 10-1 | 7.6 x 10-2 | Cu(CHO2)2 |
| 71.0 | 1 x 10-1 | 8.3 x 10-2 | Cu(CHO2)2 |
| 77.0 | 1 x 10-1 | 9.8 x 10-2 | Cu(CHO2)2 |
| 60.0 | 1.973 x 10-1 | 3.19 x 10-1 | Cu(CHO2)2 |
| 70.5 | 1.973 x 10-1 | 3.99 x 10-1 | Cu(CHO2)2 |
| 77.2 | 1.973 x 10-1 | 4.65 x 10-1 | Cu(CHO2)2 |
| 51.5 | 2.975 x 10-1 | 1.016 | 2Cu(CHO2)2·3CH2O2 |
| 68.5 | 2.975 x 10-1 | 1.286 | 2Cu(CHO2)2·3CH2O2 |
| 74.0 | 2.975 x 10-1 | 1.365 | 2Cu(CHO2)2·3CH2O2 |
| 29.0 | 3.354 x 10-1 | 1.179 | 2Cu(CHO2)2·3CH2O2 |
| 31.0 | 3.354 x 10-1 | 1.308 | 2Cu(CHO2)2·3CH2O2 |
| 33.0 | 3.354 x 10-1 | 1.501 | 2Cu(CHO2)2·3CH2O2 |
| 38.5 | 3.354 x 10-1 | 1.68 | 2Cu(CHO2)2·3CH2O2 |
| 43.0 | 3.354 x 10-1 | 1.95 | 2Cu(CHO2)2·3CH2O2 |
| 44.0 | 3.354 x 10-1 | 2.004 | 2Cu(CHO2)2·3CH2O2 |
| 37.0 | 4.375 x 10-1 | 1.99 | 2Cu(CHO2)2·3CH2O2 |
| 43.5 | 4.375 x 10-1 | 2.47 | 2Cu(CHO2)2·3CH2O2 |
| 48.5 | 4.375 x 10-1 | 2.816 | 2Cu(CHO2)2·3CH2O2 |
| 51.5 | 4.375 x 10-1 | 3.131 | 2Cu(CHO2)2·3CH2O2 |
(a) R = Number of molecules of NH4CHO2/Number of molecules (NH4CHO2 + CH2O2). (b) The authors make the following comment about this solid phase: "it contained no ammonia and therefore consisted of Cu(CHO2)2, presumably solvated."
