OXIDATION OF ETHYLENEDIAMINETETRAACETATOCOBALTATE(II) COMPLEX BY HYDROGEN PEROXIDE IN AQUEOUS ACIDIC MEDIUM: A KINETIC STUDY

The oxidation of ethylenediaminetetraacetatocobaltate(II) complex ([CoEDTA] 2- ) by Hydrogen peroxide  in aqueous perchloric acidic medium was   studied at ionic strength (I) 0.50 mol dm -3 (NaClO 4 ), T = 30 0 C , [H + ] = 1 10 -3 mol dm -3  and  λ max of  510  nm . Stoichiometric determination shows that for two moles of   the reductant, one mole of the oxidant was consumed. Kinetics study carried out under pseudo - first order condition gave result that fit into the rate law:  The study on the effect of [H + ] on the rate of reaction shows that the rate and acid concentration varies inversely and the plot of  acid dependent rate constant against [H + ] -1 was linear with  slope 2.0  10 -7 dm 3 mol -1 s -1 and intercept 1.0  10 -4 s -1 . The rate law involving acid concentration is: The  reaction displayed negative primary salt effect which suggests the composition of activated complex are oppositely charged reactants ions.  The Michaelis – Menten’s plot gave significant intercept indicative of presence of intermediate complex. On the basis of available evidence the inner - sphere mechanism is proposed for the reaction. Keywords : Oxidation, Ethylenediaminetetraacetatocobaltate(II), Complex, Hydrogen Peroxide, Kinetics