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Solubility System: Manganese formate with Iron(II) formate and Water (Original Report)

Variables:
Concentration: Composition at 25°C
Experimental Data:
w1 w2 m1 (mol/kg) [Note: $^a]m2 (mol/kg) [Note: ^a]Phase [Note: ^b]Phase
4.200.3010ALiquid
3.640.632.320.430.2610.045BLiquid
3.161.331.640.610.2270.096BLiquid
2.961.671.820.550.2130.121BLiquid
2.262.871.80.560.1630.209BLiquid
1.563.871.950.510.1130.2823BLiquid
0.675.151.570.640.0490.377BLiquid
06.2800.462CLiquid

a) The molality values were calculated by the compilers.
b) The solid phases are: A = Fe(CHO2)2·2H2O; B = (Fe,Mn)(CHO2)2·2H2O; C = Mn(CHO2)2·2H2O.

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 Fe2+. The Fe2+ content of the liquid and solid phases was determined complexometrically at pH 1.5 using Sulfosalicylic acid as indicator after preliminary oxidation of Fe2+ by H2O2. The sum of Fe2+ and Mn2+ was also determined complexometrically at pH 5.5 using Xylenol Orange as indicator after first oxidizing the Fe2+ with H2O2. 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:

(1) 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

Temperature: Not given.
Solubility: The solubility of the salts was determined in a slight excess of formic acid (about 2%) to suprress salt hydrolysis.

References:

(1) D. Trendafelov and Chr. Balarew, Comm. Dept. Chem. Bulg. Acad. Sci. 1, 73 (1968).

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