Kinetics and Mechanism of the Oxidation of Orange II by Chlorate Ion in Aqueous Hydrochloric Acid

Abstract

The kinetics of the oxidation of orange II (OR- ) by ClO3 -was studied in aqueous hydrochloric acid where the ionic strength and other parameters of the reaction mixture was, I = 0.50 mol dm-3 (NaCl), H +  = 5.0  10-2 mol dm-3 (HCl) and T = 21  1C. The redox reaction displayed a stoichiometry of 1:2 and obeys the rate law given as,−????[????????−]/???????? = ????[???? ା ][????????ି ][????????????ଷି ]. The observed second order rate constant was found to increases with increase in hydrogen ion concentration. The rates of reaction displayed a zero salt effect and was inhibited by some added cations and anions. From the Michaelis-Menton Buck plot, there was no evidence for the formation of intermediate during the course of the reaction. Based on the results obtained, the outersphere mechanism was proposed for the reaction.