Thermal decomposition of Manganese(II) oxalate in vacuum and in oxygen

Abstract

Comparative studies of the kinetics of thermal decomposition of anhydrous manganese(II) oxalate in vacuum and in oxygen are reported. Reaction rates were appreciably influenced by the conditions of salt dehydration: both decompositions were more rapid for vacuum-dehydrated reactant than for salt dehydrated in air. The shapes of product yield against time curves were not detectably changed by the presence of oxygen. The solid product from the oxidation reaction was largely Mn₂O₃ and the activation energy was significantly lower than previously reported values for the vacuum decomposition which yields MnO. Mechanistic interpretation of the kinetic data was supplemented where appropriate by observations from electron micrographs. Product gas analyses, during the course of decomposition reactions, indicated the initial formation of products containing Mn³⁺, though this was subsequently reduced. Reaction mechanisms involving the participation of Mn³⁺ in both decomposition and oxidation of manganese(II) oxalate are proposed.