Kinetics of the thermal decomposition of oxalate in molten alkali nitrates

Abstract

The thermal decomposition of oxalate in KNO 3NaNO 3 eutectic has been studied in the temperature range 250–325°C using two different techniques. In the first, the basic material produced after different fusion periods was titrated potentiometrically with standard HCl and proved to be CO 2− 3; NO − 2 formed in equivalent quantities. The second technique involved the tracing of voltammetric curves for oxalate—nitrate mixtures at different time intervals and temperatures. Three waves were recorded due to the oxidation of the remaining (COO) 2− 2 and the CO 2− 3 and NO − 2 evolved. The decomposition of oxalate, viz., (COO) 2− 2 + NO − 3 = CO 2− 3 + NO − 2 + CO 2, follows a first order rate-equation with an activation energy of 37.8 kcal mol −1. Deceleration of the reaction occurs when the melt is saturated with CO 2.