Kinetics of the decomposition and formation of ethylenedinitrilotetra-acetatovanadate(III) in dilute aqueous perchloric acid

Abstract

The kinetics of the title reaction V(Y)⇌ V³⁺+ HY have been studied spectrophotometrically in the forward direction at [H⁺]= 0.6–4.0 mol dm^–3 and in the reverse direction at [H⁺]= 0.1–1.0 mol dm^–3. V(Y) represents [V(edta)]^– together with [V(Hedta)] and [V(H₂edta)]⁺; the corresponding protonation equilibrium constants have been measured by using an e.m.f. cell under the conditions of the kinetic experiments, viz. ionic strength I= 4.0 mol dm^–3(NaClO₄) and 25.0 °C. HY represents H₄edta together with H₅edta⁺ and H₆edta²⁺. Two reaction paths have been identified for both the forward and the reverse reaction. The equilibrium constant for the reaction has been measured directly at [ H⁺]= 0.5–1.0 mol dm^–3 and its value is similar to that obtained from kinetic parameters.