KINETICS OF OXIDATION OF ANTIMONY(III) BY VANADIUM(V) IN AQUEOUS HYDROCHLORIC-ACID MEDIA

The oxidation of antimony(III) by vanadium(V) has been studied in aqueous hydrochloric acid media at 25 degrees C. It follows the rate law (i) where K-1 and K-2 are the respective equilibrium constants of the Rate = - d[V-V]/dt = kK(1)K(2)[VO2+][Sb-III][H3O+]/( 1 + K-1[H3O+])(K-2 + [Cl-] (i) reactions (ii) and (iii) and k is the rate constant of the slow step of the reaction. The data suggest [VO2](+) + H3O+ reversible arrow [V(OH)(3)](2+) (ii) [SbCl5](2-) reversible arrow [SbCl4]= + Cl- (iii) the interaction of the active species [SbCl4](-) and [V(OH)(3)](2+) in the rate-limiting stage followed by the formation of products in a subsequent fast step.