INHIBITION OF CHEMICAL OSCILLATIONS BY BROMIDE ION IN THE BRIGGS-RAUSCHER REACTION

The addition of bromide ions to the component solutions of the Briggs- Rauscher oscillating system produces a variety of phenomena, dependin g on the sequence of the addition acid on the initial bromide concentr ation. If the addition is made some minutes after the mixing of H2O2 a nd acidic IO3- and before adding malonic acid and Mn2+ ions, the oscil lations last for Eve or six cycles, then suddenly ceases. If the addit ion is made immediately after the mixing of H2O2 and acidic IO3- and b efore adding malonic acid and Mn2+ ions, the oscillations do not start at all. The addition of bromide ions to an actively oscillating BR re action causes a rapid suppression of the oscillations. Our observation s may be accounted for by a mechanism involving the IBr species. (C) 1 998 John Wiley & Sons, Inc.