THE THERMAL-DECOMPOSITION OF OXALATES .23. AN ISOTHERMAL KINETIC-STUDY INTO THE EFFECT OF THE ENVIRONMENTAL ATMOSPHERE ON THE THERMAL-DECOMPOSITION OF SILVER OXALATE

The thermal decomposition of silver oxalate has been carried out under isothermal conditions using atmospheres of nitrogen, air, oxygen and carbon dioxide, as well as under vacuum. The decomposition results obtained are treated by conventional methods to obtain the reaction mechanisms, f(alpha), and by the integral method to obtain the rate constants and hence the Arrhenius parameters. Differential scanning calorimetry (DSC) has been used to follow the energy profile of the decomposition and in each case the decomposition has been found to be exothermic and the final product to be silver metal. The exothermic nature can be explained on the basis of conventional thermodynamics, although a release of the strain set up in the solid during the decomposition is proposed to account for the unsymmetrical energy profiles obtained.