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IUPAC-NIST Solubility Database
NIST Standard Reference Database 106
Solubility System:
Cobalt formate with Copper formate and Water
Components:
(1) Cobalt formate; Co(CHO2)2; [544-18-3]
NIST Chemistry WebBook
for detail
(2) Copper formate; Cu(CHO2)2; [544-19-4]
NIST Chemistry WebBook
for detail
(3) Water; H2O; [7732-18-5]
NIST Chemistry WebBook
for detail
Original Measurements:
Stoilova, D., J. Solid State Chem. 104, 404-411 (1993).
Variables:
Concentration = Composition at 25 ºC
Prepared By:
Chr. Balarew and St. Trendafilova
Experimental Data:
(Notes on the Nomenclature)
(Please see footnotes following the table(s).)
Solubility values in the Co(CHO
2
)
2
-Cu(CHO
2
)
2
-H
2
O system at 25 °C.
Chemical
1
Phase
Mass Fraction w
1
m
1
[mol kg-1]
a
Chemical
2
Mass Fraction w
2
m
2
[mol kg-1]
a
Solid Phase(s)
b
Distribution Coefficient
Cu2+/Co2+
Distribution Coefficient
Co2+/Cu2+
Cu(CHO2)2
Liquid
8.80
0.63
Co(CHO2)2
---
---
A
---
---
Cu(CHO2)2
Liquid
8.40
0.60
Co(CHO2)2
0.50
0.04
B
2.78
0.36
Cu(CHO2)2
Liquid
8.20
0.59
Co(CHO2)2
0.70
0.05
B
1.69
0.59
Cu(CHO2)2
Liquid
8.15
0.58
Co(CHO2)2
1.02
0.08
eutonic
Cu(CHO2)2
Liquid
8.00
0.57
Co(CHO2)2
1.01
0.07
C
0.12
8.33
Cu(CHO2)2
Liquid
8.05
0.58
Co(CHO2)2
1.03
0.08
C
0.10
10.00
Cu(CHO2)2
Liquid
6.77
0.48
Co(CHO2)2
1.29
0.09
C
0.12
8.33
Cu(CHO2)2
Liquid
5.83
0.41
Co(CHO2)2
1.35
0.10
C
0.12
8.33
Cu(CHO2)2
Liquid
4.10
0.28
Co(CHO2)2
1.50
0.11
C
0.15
6.67
Cu(CHO2)2
Liquid
3.30
0.23
Co(CHO2)2
1.80
0.13
C
0.15
6.67
Cu(CHO2)2
Liquid
1.19
0.08
Co(CHO2)2
2.33
0.16
C
0.08
12.50
Cu(CHO2)2
Liquid
---
---
Co(CHO2)2
2.44
0.17
D
---
---
Notes:
a
The molality values were calculated by the compilers.
b
The solid phases are: A = Cu(CHO
2
)
2
•4H
2
O; B = (Cu,Co)(CHO
2
)
2
•4H
2
O; C = (Co,Cu)(CHO
2
)
2
•2H
2
O; D = Co(CHO
2
)
2
•2H
2
O.
Method/Apparatus/Procedure:
The solubility was studied by the method of isothermal decrease of supersaturation. The equilibrium was reached in about two days. The liquid phase concentrations were determined as follows. The sum of the copper and cobalt formate concentrations was determined complexometrically at
p
H 5.5-6.0 using Xylenol orange as indicator, the copper formate concentration was determined iodometrically. The cobalt formate concentration was estimated by difference. The variation of the Schreinemakers' method was used for calculation of ideally suction dried solid phase composition.
1
X-ray powder analysis and IR spectra were carried out.
Source and Purity of Materials:
The metal formates were prepared from reaction of the corresponding metal hydroxide carbonates with dilute formic acid solutions at 70-80 °C. The crystals were recrystallized in water and dried in air. The reagents used were p.a.(Merck).
Estimated Errors:
Solubility: The experiments were carried out in presence of a slight excess of formic acid (1-2 mass %) in order to suppress the salt hydrolysis.
Temperature: Not given.
References:
1
D. Trendafelov and Chr. Balarew, Comm. Dept. Chem. Bulg. Acad. Sci.
1
, 73 (1968).