Transition from Low to High Iodide and Iodine Concentration States in the Briggs–Rauscher Reaction: Evidence on Crazy Clock Behavior

Maja C. Pagnacco, Jelena P. Maksimović, Nebojša I. Potkonjak, Bojan Đ. Božić, Attila K. Horváth

The Briggs-Rauscher reaction containing malonic acid may undergo a sudden transition from low (state I) to high iodide and iodine (state II) concentration states after a well-defined and strongly reproducible oscillatory period. This study clearly shows that even though the time-dependent behavior of the oscillatory state is reproducible, the time lag necessary for the appearance of the state I to state II transition after the system leaves the oscillatory state becomes irreproducible for an individual kinetic run. This crazy clock behavior of the state I→state II transition is identified by repeated experiments, in which stirring rate is taken as a control parameter and all other parameters such as initial conditions, temperature, vessel surface and the age of solution were kept constant. Surprisingly, a better stirring condition does not make the transition to be reproducible; it simply does not allow the transition to happen at all. The proposed mechanism, additional explanations as well as proposals for this irreproducibility of state I to state II transition have been presented. Considering the fact that the number of crazy-clock reactions is only a few, this study may contribute to a better understanding of fundaments of this phenomenon.