At I = 0.50 mol dm-3 (NaCl), T = 21 ± 1oC, [H+] = (0.6-1.8) x 10-2 mol dm-3, the oxidationreduction reaction between pyrocatechol violet (hereafter referred to PCVH) and chlorite ions have been studied and has a stoichiometry of 1:1. The reaction is second-order overall, firstorder in both oxidant and reductant. The reaction occurs by parallel acid independent and aciddependent pathways suggesting HClO- and ClO2 - as the principal reactant chlorite species. The second order rate constant increases with increase in acid concentration and decrease with an increase in ionic strength of the reaction medium. The reaction rate was mildly reduced by anions SO4 2- and HCOO-. The test for free radicals was negative. The kinetic data are consistent with the following equation: ( [ ])[ ][ ] [ ] 2 2 + - - = a + b H PCVH ClO dt d ClO The experimental results are in favour of the outer-sphere mechanisms
