Abstract
It has been found that the reported permanent inhibition of concentration oscillations by trace amounts of chloride ion added to the bromate-cerium-malonic acid system is of only temporary duration. The effects of adding chloride to the system under a variety of conditions are reported, and a mechanism to explain these effects is proposed. The chloride inhibi- tion mechanism involves the oxidation of chloride to chlorous acid, which then reduces Ce(IV) to Ce(IlI), preventing oscilla- tion. The oscillations resume when the chlorous acid has been completely oxidized to chlorate. The overall reaction is 2C1- + 3Br03" + 3H+ — 3HOBr + 2C103-.