Chemical Oscillators in Group VIA: The Cu(II)-Catalyzed Reaction between Hydrogen Peroxide and Thiosulfate Ion

Abstract

In the presence of small amounts (~10-5M) of Cu(II), the reaction between hydrogen peroxide and thiosulfate ion in a stirred tank reactor exhibits one oscillatory and three stationary states as well as bistability between the oscillatory and one of the stationary states and between two stationary states. The amplitude of the oscillations can be as large as 4 pH units or 200 mV in the potential of a Pt redox electrode. Near the bistable regions, the system undergoes large over- and undershoots as the flow rate is varied. In the absence of the copper catalyst, only a single steady state is found, with no unusual dynamical phenomena. Some tentative mechanistic suggestions are offered to account for this behavior. © 1987, American Chemical Society. All rights reserved.