A kinetic study of the reduction of the octacyanomolybdate(V) ion by the hydroxide ion

Abstract

The kinetics of the oxidation of hydroxide ions by octacyanomolybdate(V) ions has been studied in the [OH−] range between 0.5 and 4.0 mol dm−3. The reaction displays first-order kinetics in both [Mo(CN)83−] and [OH−] and is consistent with the rate law R = k [Mo(CN)83−] [OH−]. From the Bronsted-Bjerrum equation, it was established that the activated complex is formed by the ions Mo(CN)83− and OH−. A reaction mechanism is proposed for the reaction with a rate constant of 1.13 ± 0.03 × 10−2 dm3 mol−1 s−1, activation enthalpy, ΔH#, of 20.1 ± 09 kJ mol−1 and activation entropy, ΔS*, of −213 ± 3 J K−1 mol−1.