Abstract
The autocatalytic reaction between chlorite and iodide ions in a closed system is a clock reaction, showing a sudden appearance of brown I2 followed by a rapid disappearance of the color. Under certain conditions, the reaction time displays a striking irreproducibility. This stochastic behavior is studied potentiometrically and spectrophotometrically as a function of initial [I− ], stirring rate and solution volume. The results imply that the irreproducibility is an inherent feature of the reaction generated by fluctuations in the solution after it is ‘‘well mixed.’’ The key contributors to the stochasticity are local concentration in homogeneities resulting from imperfect stirring and the ‘‘supercatalytic’’ reaction kinetics. A qualitative explanation is given that incorporates these aspects.