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IUPAC-NIST Solubility Database
NIST Standard Reference Database 106
Solubility System:
Magnesium formate with Copper(II) formate and Water
Components:
(1) Magnesium formate; Mg(CHO2)2; [557-39-1]
NIST Chemistry WebBook
for detail
(2) Copper(II) 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.; Balarew, C.; Vassileva, V., Comm. Dept. Chem. Bulg. Acad. Sci. 18, 3 (1985).
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 Mg(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+/Mg2+
Distribution Coefficient
Mg2+/Cu2+
Mg(CHO2)2
Liquid
11.96
1.188
Cu(CHO2)2
0.00
0.00
A
Mg(CHO2)2
Liquid
11.20
1.113
Cu(CHO2)2
0.81
0.06
B
2.28
---
Mg(CHO2)2
Liquid
9.68
0.964
Cu(CHO2)2
2.52
0.187
B
1.61
---
Mg(CHO2)2
Liquid
8.94
0.895
Cu(CHO2)2
3.75
0.280
B
1.55
---
Mg(CHO2)2
Liquid
8.91
0.902
Cu(CHO2)2
4.68
0.353
B
1.35
---
Mg(CHO2)2
Liquid
7.43
0.766
Cu(CHO2)2
7.74
0.594
B+C
eutonic
Mg(CHO2)2
Liquid
6.10
0.618
Cu(CHO2)2
7.52
0.567
D
---
0.06
Mg(CHO2)2
Liquid
4.42
0.439
Cu(CHO2)2
7.47
0.552
D
---
0.05
Mg(CHO2)2
Liquid
1.50
0.145
Cu(CHO2)2
8.11
0.584
D
---
0.05
Mg(CHO2)2
Liquid
0.00
0.00
Cu(CHO2)2
8.80
0.628
E
Notes:
a
The molality values were calculated by the compilers.
b
The solid phases are: A =Mg(CHO
2
)
2
•2H
2
O; B = (Mg,Cu)(CHO
2
)
2
•2H
2
O; C = (Cu,Mg)(CHO
2
)
2
•2H
2
O; D = (Cu,Mg)(CHO
2
)
2
•4H
2
O; E = Cu(CHO
2
)
2
•4H
2
O.
Method/Apparatus/Procedure:
The method used was the isothermal decrease of supersaturation, under stirring, for 15-20 hrs. The Cu
2+
content of the liquid and solid phases was determined complexometrically using Complexon III at
p
H 5.5-6.0 and Xylenol Orange as indicators. The Mg
2+
concentration was determined complexometrically using Complexon III at pH 9.5-10 and Eriochrome Black T as indicators, after masking the Cu
2+
with cyanide ions. The composition of the suction-dried mixed crystals was determined by the algebraic indirect identification of the solid phase composition method.
1
Source and Purity of Materials:
Analytical Reagent grade substances were used. The copper and magnesium formates were obtained by neutralizing dilute formic acid solutions with the corresponding hydroxide carbonates.
Estimated Errors:
Solubility: The solubility of the salt is determined in a slight excess of formic acid (about 2%) to suppress salt hydrolysis.
Temperature: Not given.
References:
1
D. Trendafelov and Chr. Balarew, Comm. Dept. Chem. Bulg. Acad. Sci.
1
, 73 (1968).