Spectrophotometric studies of reaction rates under high pressure

Abstract

Activation volumes for the aquation of dichloro-bisethylene diamine cobalt(III) ion and the bromate-iodide reaction were measured using a spectrophotometric technique. Values of ΔV* were +5 ± 2 cm3 mol-1 and -3 ±1cm3 mol-1 respectively. The positive value of ΔV* obtained for the aquation reaction and also its independence of pressure supports the suggestion that the mechanism is a dissociative controlled process. This agrees with previous observations. The small negative value of ΔV* obtained for the bromate-iodide reaction is discussed in terms of a neutralisation mechanism using a previous model. It is also compared with the related bromate-bromide reaction.