THERMAL-DECOMPOSITION OF CADMIUM SULFATE

The thermal decomposition of CdSO4 in the form of a disk-shaped pellet was studied in flowing high-purity nitrogen by use of an electrobalance. As the product oxide was vaporised at temperatures as high as 1000°C, the decomposition rate constant was determined below 840°C. The reaction proceeded from the surface of a pellet yielding an oxide layer. The growing rate of the layer fitted an equation derived from a model in which the rate-determin- ing step is the decomposition reaction, dx/dt = k, where k is a rate constant, x is the oxide layer thickness and t is time. The activation energy for the decomposition of CdSO4 was 289 kJ mol-1, which was close to the enthalpy of the decomposition of CdSO4. © 1990.