Kinetic study of the acid decomposition of decavanadate

Abstract

The reaction of decavanadate at concentration of 0·5 × 10^–2 and 0·5 × 10^–3 mol dm^–3 with acid was followed by use of a stopped-flow spectrophotometer, ionic strength being maintained with sodium nitrate. A plot of pseudo-first-order rate constant against hydrogen ion concentration showed that at high acid concentrations (>0·2M) the rate constant increased linearly with acid concentration, but that the line obtained had a finite positive intercept on the acid concentration axis. The suggested mechanism involves equilibria between H₂V₁₀O₂₈^4–, H₃V₁₀O₂₈^3–, and H₄V₁₀O₂₈^2–, with decomposition occurring through H₄V₁₀O₂₈^2–.