Exchange current density as control for oscillatory reactions

The oscillation characteristics of the iodate systems (Briggs-Rauscher reaction) and the bromate system (Belousov-Zhabotinskii reaction) with ethylacetoacetate show that the species responsible for the oscillations in these two systems are different. This arises from a large value of the exchange current density for Pt/I2/I-. The inclusion of ferroin in an uncatalysed bromate system (ubs) leads to a switchover to a new oscillatory phase, catalysed bromate system (cbs). Oscillation in ubs is caused by a periodic change in the concentration of bromine. The switchover in oscillation characteristics on the addition of ferroin results from the value of the exchange current density for Pt/Fe(III)/Fe(II) being larger than Pt/Br2Br-. © 1983 Indian Academy of Sciences.