Thermal decomposition of 2,3,5-triphenyl, tetrazolium halochromate complexes

Abstract

Thermal decomposition studies of 2,3,5-triphenyl tetrazolium halochromates have been carried out upto 1000 degrees C at a linear heating rate of 10 deg . min(-1). The complexes undergo two stage decomposition. First one corresponds to the redox decomposition of the complex along with the loss of a phenyl halide molecule and 3/2 mol of oxygen. While, the second step corresponds to the oxidation of the formazan type structure formed in the first step. The first step decomposition follows diffusion controlled reaction mechanism in a sphere governed by the equation g(alpha)=[1 - (1 - alpha)(1/3)](2). Activation energy and pre-exponential factors have been determined by Coats-Redfern model and Dixit-Ray model. Activation energy decreases as the electronegativity of the halide ion decreases.