(B-Z reaction (Belousov-Zhabotin­skii reaction

 A chemical reaction that shows a periodic colour change between magenta and blue with a pe­riod of about one minute. It occurs with a mixture of sulphuric acid, potassium bromate(V), cerium sul­phate, and propanedioic acid. The colour change is caused by alternat­ing oxidation-reductions in which cerium changes its oxidation state (Ce³⁺ gives a magenta solution while Ce⁴⁺ gives a blue solution). The B-Z reaction is an example of a chemical *oscillating reaction – a reaction in which there is a regular periodic change in the concentration of one or more reactants. The mechanism is highly complicated, involving a large number of steps.