Components:
(1) Copper formate,
Cu(CHO2)2; [544-19-4]
NIST WebBook
(2) Zinc formate,
Zn(CHO2)2; [557-41-5]
NIST WebBook
(3) Water,
H2O; [7732-18-5]
NIST WebBook
Original Measurements
Stoilova, D.; Gentcheva, G.; J. Solid State Chem. 100, 24-9 (1992).
Variables:
Ambient temperature: Composition at 50 °C
Prepared by:
St. Trendafilova, Chr. Balarew
Method/Apparatus/Procedure:
The method used was the isothermal decrease of supersaturation. Equilibrium was reached in about two days. The total copper and zinc formate concentrations of the liquid and solid phases was determined complexometrically at pH 5.5-6.0 using Xylenol Orange as indicator. The copper formate concentration was determined iodometrically. The zinc formate concentration was calculated by the difference. The composition of the suction-dried solid phase was determined by using a modification of the Schreinemakers method. 1 The solid phase was also studied by x-ray diffraction.
Source and Purity of Materials:
- The metal formates were prepared by the reaction of the corresponding basic carbonate (for copper formate) or the metal oxide (for zinc formate) with dilute formic acid solutions. Analytical grade reagents were used.
Estimated Errors:
Ambient temperature: Not given.
Mass concentration (m/v) (1): The solubility of the salts was determined in a slight excess of formic acid (about 1-2 mass%) to suppress salt hydrolysis.
References
1 Trendafelov, D.; Balarew, Chr.; Comm. Dept. Chem. Bulg. Acad. Sci. 1 , 73 (1968).
Experimental Values:
Solubility values in the Cu(CHO2)2-Zn(CHO2)2-H2O system at 50°C.
| 100w1 | 100w2 | D1|2 | D2|1 | m1 (mol/kg)a | m2 (mol/kg)a | Phase (s)b |
|---|---|---|---|---|---|---|
| - | 8.06 | - | - | 5.64 x 10-1 | - | A |
| 2.59 | 6.89 | 2.6 x 10-1 | 3.84 | 1.86 x 10-1 | 4.90 x 10-1 | B |
| 5.88 | 5.8 | 1.9 x 10-1 | 5.26 | 4.33 x 10-1 | 4.23 x 10-1 | B |
| 9.43 | 5.44 | 2.0 x 10-1 | 5.0 | 7.21 x 10-1 | 4.11 x 10-1 | B |
| 13.63 | 3.79 | 1.7 x 10-1 | 5.88 | 1.075 | 2.95 x 10-1 | B |
| 19.19 | 3.16 | 1.2 x 10-1 | 8.32 | 1.609 | 2.62 x 10-1 | B |
| 23.85 | 3.0 | 1.4 x 10-1 | 7.14 | 2.123 | 2.64 x 10-1 | B |
| 25.06 | 2.89 | - | - | 2.265 | 2.58 x 10-1 | Eutonic |
| 25.6 | 2.52 | - | - | 2.319 | 2.26 x 10-1 | Eutonic |
| 26.24 | 2.95 | - | - | 2.413 | 2.68 x 10-1 | Eutonic |
| 26.31 | 2.26 | 3.7 x 10-1 | 2.7 | 2.398 | 2.04 x 10-1 | C |
| 27.63 | 1.17 | 3.7 x 10-1 | 2.7 | 2.527 | 1.06 x 10-1 | C |
| 27.58 | 3.8 x 10-1 | 3.6 x 10-1 | 2.78 | 2.493 | 3.4 x 10-2 | C |
| 26.92 | 2.0 x 10-1 | 3.3 x 10-1 | 3.03 | 2.405 | 1.8 x 10-2 | C |
| 25.17 | - | - | - | - | 2.19 | C |
(a) The molality values were calculated by the compilers. (b) The solid phases are: A = Zn(CHO2)2·2H2O; B = (Zn,Cu)(CHO2)2.·2H2O; C = (Cu,Zn)(CHO2)2·2H2O; and D = Cu(CHO2)2·2H2O.
