Novel experimental findings in the B–Z system employing mixed substrates

Certain novel features of the Belousov–Zhabotinsky (B–Z) system employing different mixed substrates and Mn(II) as the catalyst are presented. Malic acid is the common substrate together with one of malonic, citric, cyanoacetic, maleic, acetic, oxalic, or tartaric acid as the second substrate. The correlation of the oscillatory behaviour with values of exchange current density establishes the oscillatory control by the redox couple, namely, Mn(III)/Mn(II) and (or) Br2/Br−. Each substrate when used alone gives rise to an oscillatory behaviour with characteristic features that can be compared with the system containing mixed substrate. The combination of substrates provides different modes of oscillatory behaviour such as entrainment, independent, partial inhibition, or complete inhibition. These observations are rationalized in terms of relevant steps involved in the mechanism of the reaction. Key words: mixed substrate, exchange current density, entrainment, independent, inhibition.