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IUPAC-NIST Solubility Database
NIST Standard Reference Database 106
Solubility System:
Manganese formate with Iron(II) formate and Water
Components:
(1) Iron(II) formate; Fe(CHO2)2; [3047-59-4]
NIST Chemistry WebBook
for detail
(2) Manganese formate; Mn(CHO2)2; [3251-96-5]
NIST Chemistry WebBook
for detail
(3) Water; H2O; [7732-18-5]
NIST Chemistry WebBook
for detail
Original Measurements:
Stoilova, D.; Balarew, C.; Vassileva, V., J. Solid State Chem. 57, 260-6 (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 Mn(CHO
2
)
2
-Fe(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
Fe2+/Mn2+
Distribution Coefficient
Mn2+/Fe2+
Fe(CHO2)2
Liquid
4.2
0.301
Mn(CHO2)2
0.00
0.00
A
---
---
Fe(CHO2)2
Liquid
3.64
0.261
Mn(CHO2)2
0.63
0.045
B
2.32
0.43
Fe(CHO2)2
Liquid
3.16
0.227
Mn(CHO2)2
1.33
0.096
B
1.64
0.61
Fe(CHO2)2
Liquid
2.96
0.213
Mn(CHO2)2
1.67
0.121
B
1.82
0.55
Fe(CHO2)2
Liquid
2.26
0.163
Mn(CHO2)2
2.87
0.209
B
1.80
0.56
Fe(CHO2)2
Liquid
1.56
0.113
Mn(CHO2)2
3.87
0.2823
B
1.95
0.51
Fe(CHO2)2
Liquid
0.67
0.049
Mn(CHO2)2
5.15
0.377
B
1.57
0.64
Fe(CHO2)2
Liquid
0.00
0.00
Mn(CHO2)2
6.28
0.462
C
---
---
Notes:
a
The molality values were calculated by the compilers.
b
The solid phases are: A = Fe(CHO
2
)
2
•2H
2
O; B = (Fe,Mn)(CHO
2
)
2
•2H
2
O; C = Mn(CHO
2
)
2
•2H
2
O.
Method/Apparatus/Procedure:
The method used was the isothermal decrease of supersaturation, under stirring, for 15-20 hrs. in an argon atmosphere to prevent oxidation of Fe
2+
. The Fe
2+
content of the liquid and solid phases was determined complexometrically at
p
H 1.5 using Sulfosalicylic acid as indicator after preliminary oxidation of Fe
2+
by H
2
O
2
. The sum of Fe
2+
and Mn
2+
was also determined complexometrically at
p
H 5.5 using Xylenol Orange as indicator after first oxidizing the Fe
2+
with H
2
O
2
. The composition of the suction-dried mixed crystals was determined by the algebraic indirect identification of the solid phase composition method.
1
They were also studied by X-ray diffraction.
Source and Purity of Materials:
The reagents used were of p. a. grade. Manganese formate was prepared by the action of dilute formic acid with manganese carbonate. The iron formate was prepared by dissolving powdered iron in dilute formic acid.
Estimated Errors:
Solubility: The solubility of the salts was determined in a slight excess of formic acid (about 2%) to suprress salt hydrolysis.
Temperature: Not given.
References:
1
D. Trendafelov and Chr. Balarew, Comm. Dept. Chem. Bulg. Acad. Sci.
1
, 73 (1968).