The thermal decomposition of oxalates. Part X. Nitrogen adsorption data on solid residues from the isothermal heat treatment of manganese(II) oxalate dihydrate

Abstract

The surface areas of the solid residues from the isothermal heat treatment of manganese(II) oxalate dihydrate are determined. The dehydration reaction kinetics between 100–200° are described by a contracting envelope equation and an activation energy (18·3 kcal. mole^–1) lower than previously reported. This could be due to the presence of defects similar to those caused by irradiation of the hydrated salt. The anhydrous oxalate produced under these conditions was crystalline and this influences the subsequent decomposition to the oxide. The energy of activation is 33·8 kcal. mole^–1 which is lower than previously reported for the decomposition of amorphous anhydrous manganese(II) oxalate. The adsorption data indicates that the oxide produced at 310° is in the form of plates but that these sinter extensively at higher temperatures.