Mapping Sequential Oscillations in the Bromate–OxalicAcid–Acetone–Ce(IV) Reaction

摘要

Oscillating reactions are reactions in which it is possible to observe oscillations in the concentrations of some reaction intermediates. The reaction studied here is composed of acetone, sulfuric acid, bromate, oxalic acid, and Ce(IV). Chemical oscillators may have different behaviors in batch, for example, the presence of an induction period and change of oscillations’ pattern. A much rarer event is the presence of a break, or pause, between two groups of oscillations, which is shown by this system. To better determine the conditions under which this behavior occurs, we built several phase diagrams for the initial concentrations of reactants. These phase diagrams show that there is a well-defined range of concentrations that produce a pause in the oscillations. The initial bromate concentration is special because increasing this concentration eliminates the pause in the oscillations, but a further increase can make a pause appear again. These results can be interpreted considering that the reaction mechanism is controlled by at least two intermediates. In addition, this work presents a representativeset of data that must be acknowledged by any detailed proposal ofmechanism for this oscillating reaction.