Kinetics and mechanism of oxidation of semicarbazide by Keggin type 12-tungstocobaltate(III) in acidic medium

The kinetics of oxidation of semicarbazide by 12-tungstocobaltate (III) in aquous acidic medium at 300K and a constant ionic strength of 0.3 mol dm-3 was studied spectrophotometrically at λmax 624nm under pseudo first-order conditions. The reaction between semicarbazide and 12-tungstocobaltate (III) in acidic medium exhibits 1:2 stiochiometry [Semicarbazide:12-tungstocobaltate (III)]. The main oxidative products were indentified by Spot test and spectral studies. The effect of [H+ ] ion and ionic strength of the reaction medium have been investigated. The reaction constants involved in the different steps of the mechanism are calculated. From the log k versus 1/T values of activation parameters have been evaluated. The activation parameters with respect to the slow steps of the mechanism are computed and discussed.