Temperature dependence of the frequencies in temporal oscillations and of the moving-wave velocities of concentric waves in spatial oscillation in the Belousov-Zhabotinskii reaction was studied in detail using the same starting concentrations of the reactants. When cerium ions were used as catalyst, the activation energies were found to be 60–65 kJ/mol for the temporal oscillation and 46±4 kJ/mol for the spatial oscillation. The difference in the activation energies was well explained by the theoretical prediction based on kinetic-diffusion coupling. When [Fe(phen)32+] or [Fe(bpy)32+] was used as catalyst, the apparent activation energy in the temporal oscillation depends markedly on the concentration of the catalyst used.

Distinct Activation Energies for Temporal and Spatial Oscillations in the Belousov-Zhabotinskii Reaction

Benzylmalonic acid (BzMA) reacts via an enol mechanism with aqueous iodine to form rather stable iodobenzylmalonic acid. In the presence of iodate, which oxidizes iodide to di-iodine, the reaction goes to completion. The kinetics of the reaction BzMA + I2 + IO3− + H+ have been studied and the results were interpreted with a suitable mechanism. In a mixture with acidic iodate, hydrogen peroxide, and manganous ions, BzMA can serve as a substrate for a Briggs–Rauscher-type oscillating reaction. The behavior of this oscillator has been studied in detail. A mechanistic interpretation of the oscillations based on a new kinetic model is also given. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 357–365, 2002

Benzylmalonic acid reaction with iodine and behavior in a Briggs–Rauscher oscillator

The oscillation characteristics, investigated by potentiometry, of the bromate-Mn(II)/Ce(III)-malic acid system are presented. The induction period characteristic of the oscillatory system is analysed. The results are compared with the malonic acid and citric acid systems and are correlated with the difference in the rate of bromide production, proposed as the control intermediate.

Oscillations in the bromate system with malic acid as the substrate

Describes the effect of temperature on the time of oscillations and the determination of the apparent energy of activation of the overall process.

C. S. Swamy

Papers

Oscillations in the iodate-Mn2+ system: Apparent energy of activation