Chemistry and Mathematics of the Belousov-Zhabotinsky Reaction in a School Laboratory

Chemical reactions far from equilibrium can exhibit oscillatory behavior. Full understanding of this phenomenon is outside of the school curriculum. However, the importance of such processes in life sciences and peculiar spatial and temporal patterns accompanying the reactions can attract the attention of IB Diploma science students. They will have studied chemical kinetics and received sufficient background knowledge in ordinary differential equations in order to be able to appreciate how sceptical the scientific community was when chemical oscillations were first reported. In this article, the famous Belousov-Zhabotinsky (BZ) reaction is investigated, which involves oxidation of malonic acid to carbon dioxide by bromate ions in the presence of a transition metal catalyst. Cerium(IV) and Manganese (II) catalysts at different initial concentrations are used with the research goal of determining the influence of the catalyst on the way the oscillatory stage is established and on the properties of oscillations. Convincing evidence of oscillatory behavior is observed and quantified by digital video processing. The BZ reaction mechanism is reviewed on the basis of the Field, Koros, and Noyes (FKN) model in reduced Oregonator form. The resulting system of nonlinear differential rate equations is solved numerically, and a remarkable agreement of the theoretically predicted oscillation period with an experiment for a Cerium(IV) catalyst is achieved.