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Chemical reactions

The Belousov-Zhabotinsky reaction takes place in a fairly exotic environment, since certain chemicals have to be chosen; one of them is an indicator, whose color changes permit the reaction to be visualized. The ingredients are the same as for the other examples; a system occupies a fairly precarious equilibrium in which an exothermic reaction can be triggered.

Once underway, the production of heat and exhaustion of the reactants eventually stops the reaction, which has to wait for a new supply of reagent to diffuse into the region and for the mixture to cool before starting up again. The reaction occasionally becomes self-sustaining, with spiral waves radiating out from permanent foci.

Harold V. McIntosh