Kinetic study on the thermal decomposition of copper(II) oxalate

Abstract

The thermal decomposition of copper(II) oxalate has been studied under vacuum using a constant-volume apparatus and a microbalance; and under dynamic atmospheres of air, nitrogen and oxygen using thermogravimetry and differential scanning calorimetry. The decomposition was found to proceed to copper metal under an inert atmosphere and vacuum; while in air and oxygen, copper(II) oxide was found to be the decomposition product. In each case the decomposition was found to be exothermic with an enthalpy change of –9 ± 2 kJ mol^–1 in nitrogen and –134 ± 5 kJ mol^–1 in air. Isothermal kinetic analysis showed the data to fit an Avrami–Erofeev relationship with n= 3 in each case. Arrhenius parameters are reported for each decomposition atmosphere and are compared to those of other transition-metal oxalates which appear in the literature.

The presence of a preparation effect is noted, as seen with other oxysalts; however, no evidence for the formation of copper(I) oxlate has been found which has previously been speculated to be an intermediate in the decomposition.