Kinetics of oxidation of antimony(III) by vanadium(V) in aqueous hydrochloric acid media

Abstract

The oxidation of antimony(III) by vanadium(V) has been studied in aqueous hydrochloric acid media at 25 °C. It follows the rate law (i) where K₁ and K₂ are the respective equilibrium constants of the Rate =–d[V^V]//_dt=kK₁K₂[VO₂⁺][Sb^III][H₃O⁺]//_{(1+K1[H3O⁺])(K2+[Cl^–])(i)} reactions (ii) and (iii) and k is the rate constant of the slow step of the reaction. The data suggest [VO₂]⁺+ H₃O⁺⇌[V(OH)₃]²⁺(ii), [SbCl₅]^2–⇌[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.