Kinetics of reaction between vanadium(V) and iodide ions in the presence of oxygen

Abstract

The kinetics of reduction of vanadium(V) by iodide ions in aqueous solution have been investigated in the presence of oxygen at 25 °C and ionic strength 0·4M(NaClO₄). The results show that the reaction occurs through two parallel paths (i), the first being oxygen-independent, the second involving a molecule of O₂. The term b(s^–1)v=a+b[O₂](i) is given by equation (ii). The mechanism of the oxygen-dependent path involves formation of a peroxovanadium(V)b=(3·3 ± 0·5)× 10³[H₄VO₄⁺][I^–]²[H⁺]²(ii) intermediate, [VO(O₂)]⁺, which, rapidly reacting with iodide ions, regenerates vanadium(V), VO₂⁺, ions.