Components:
(1) Strontium formate,
Sr(CHO2)2; [592-89-2]
NIST WebBook
(2) Copper formate,
Cu(CHO2)2; [544-19-4]
NIST WebBook
(3) Water,
H2O; [7732-18-5]
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Original Measurements
Vasileva, V.; Cryst. Res. Technol. 30, 339-343 (1995).
Variables:
Ambient temperature: Composition at 25 °C
Prepared by:
St. Trendafilova, Chr. Balarew
Method/Apparatus/Procedure:
The solubility in the system was studied by the Khlopin method of isothermal decrease of supersaturation.1 Equilibrium was reached in 10-15 hr. Cu2+ was determined complexometrically at pH 5.5-6.0 using Xylenol Orange as indicator. Sr2+ was determined also complexometrically at pH 11 using Thymolphtalexon as indicator. The solid phase composition was determined by the graphic method of Schreinemakers' for wet residues. X-ray diffraction analysis, DT and TG analysis were also used.
Source and Purity of Materials:
- The formates of copper and strontium were prepared by dissolving copper carbonate, and strontium carbonate respectively, in diluted formic acid. The reagents used were "p.a.''.
Estimated Errors:
Ambient temperature: Not given.
References
1 Balarew, Chr.; Karaivanova, V.; Oikova, T.; Comm. Dept. Chem. Bulg. Acad. Sci. 3, 637 (1970).
Experimental Values:
Solubility values in the Sr(CHO2)2-Cu(CHO2)2-H2O system at 25°C.
| 100w2 | 100w1 | m2 (mol/kg)a | m1 (mol/kg)a | Phase (s)b |
|---|---|---|---|---|
| 8.8 | 0.0 | 6.28 x 10-1 | 0.0 | A |
| 7.7 | 3.77 | 5.66 x 10-1 | 3.74 x 10-1 | A |
| 7.6 | 5.75 | 5.71 x 10-1 | 3.74 x 10-1 | A |
| 8.07 | 8.63 | 6.30 x 10-1 | 5.83 x 10-1 | A |
| 8.95 | 10.7 | 7.25 x 10-1 | 7.50 x 10-1 | A |
| 9.09 | 11.18 | 7.42 x 10-1 | 7.89 x 10-1 | Eutonic |
| 9.12 | 11.15 | 7.45 x 10-1 | 7.87 x 10-1 | Eutonic |
| 8.52 | 10.9 | 6.88 x 10-1 | 7.61 x 10-1 | B |
| 7.93 | 10.8 | 6.35 x 10-1 | 7.48 x 10-1 | B |
| 7.0 | 11.16 | 5.57 x 10-1 | 7.67 x 10-1 | B |
| 4.9 | 11.15 | 3.80 x 10-1 | 7.47 x 10-1 | B |
| 3.82 | 10.99 | 2.92 x 10-1 | 7.26 x 10-1 | B |
| 3.22 | 11.35 | 2.45 x 10-1 | 7.48 x 10-1 | Eutonic |
| 2.51 | 11.72 | 1.90 x 10-1 | 7.69 x 10-1 | C |
| 0.0 | 12.2 | 0.0 | 7.82 x 10-1 | C |
(a) The molality values were calculated by the compilers. (b) The solid phases are: A = Cu(CHO2)2·4H2O; B = CuSr(CHO2)4·8H2O; C = Sr(CHO2)2·2H2O.
