Cinétique et mécanisme des réactions bromate–chlorite et bromate – dioxyde de chlore

Abstract

In an acidic solution, containing initially chlorous acid and bromate in excess, two consecutive reactions are observed, the oxidation of chlorous acid to chlorine dioxide followed by the oxidation of chlorine dioxide: BrO3− + 4ClO2 + 2H2O = 4ClO3− + 3H+ + HOBr. The kinetics of this reaction has been studied and a mechanism proposed. It agrees with the one accepted for the related reaction between bromate and Ce(III). Extended by reactions of chlorous acid, the mechanism reproduces the experimental curves of chlorine dioxide evolution in chlorous acid – bromate solutions. The values of the equilibrium and kinetic constantes are discussed.