Catalyst, Mixed Catalyst and Additive Effects on the Oscillatory Behaviour of Pyrogallol based Chemical Oscillator

Abstract

The present work is aimed to investigate the effect of the  metal ions used as single as well as mixed catalysts and Mo(VI) ion as additive on the oscillatory behaviour of the reaction system comprising of pyrogallol (1,2,3-trihydroxybenzene) as organic substrate and inorganic bromate as oxidant in aqueous sulphuric acid medium (1.5 mol L^-1). The reactions were monitored both spectrophotometrically and potentiometrically. From kinetic study, the order of reactivity of the metal ions towards oscillatory behaviour of  the bromate driven pyrogallol based chemical oscillator was found to be Mn(II) › Ce(IV) › Ce(III). The Mn(II) and Ce(IV) metal ion solutions were mixed together in order to have their mixed catalyst effect on the aforesaid system. Further, the Mo(VI) ion used as additive was found to enhance the rate of Ce(IV) catalysed reaction system owing to the fact that there is decrease in the induction period which has been found to be linearly proportional to the concentration of Mo(VI) ion in the range of 0.00225–0.02225 mol L^-1 with a correlation coefficient of 0.991 under the optimal conditions of the reaction system. The order of reactivity of the metal ions towards oscillatory behaviour of the bromate driven pyrogallol based chemical oscillator was found to be Mn(II) › Ce(IV) › Ce(III). Further, the Mo(VI) ion used as additive was found to decrease the induction period in a linear fashio