Kinetic investigations of the uncatalysed bromate-iodide and iodate-iodide reactions

Abstract

A non-buffer method is used for kinetic investigation of the bromate-iodide and iodate-iodide reactions in pH region between 3.000 and 4.000. The fifth order rate law for uncatalysed iodate-iodide reaction is found to hold in this pH region in a nitrate medium with unit ionic strength at 25°C. k0 is found to be 2.2±0.2x10 8 mol-4dm-12s-1. For the uncatalysed bromate-iodide reaction a change in rate law is observed. The rate law found in the present work is in nitrate medium with unit ionic strength at 25°C. The values of k0, k1 are 42±3 mol-3dm-9s-1 and 0.0112±0.0006 mol-2dm-6s-1 respectively. The mechanism for the new rate law for the uncatalysed bromate-iodide reaction is also discussed.