Evaluation of the Effect of Temperature on the Stability of Metal Soaps of Dicarboxylic Acids

The thermal stability of calcium and zinc dicarboxylates was studied. The kinetics of the decomposition was studied thermogravimetrically at various temperatures. The rates of the first stage decomposition were used to assess the effect of temperature on the susceptibility of the metal soaps of dicarboxylic acids to decomposition. Although the values of the rate constant for the decomposition of the soaps were about the same order of magnitude (10^-1s^-1), the soaps of glutaric acid were relatively more stable than the soaps of succinic acid. The values of the rate constant were also observed to be temperature dependent. The enthalpy, entropy and free energy of activation for the decomposition of the metal dicarboxylates were also determined. The thermodynamic values obtained showed that the system is exothermic and that the reaction process is not a spontaneous one.