Chemical clock

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A chemical clock is a complex mixture of reacting chemical compounds in which the concentration of one or more components exhibits periodic changes. In cases where one of the reagents has a visible color, crossing a concentration threshold can lead to an abrupt color change, which may be used to tell time^{[citation needed]}. Examples of clock reactions are the Belousov-Zhabotinsky reaction, the Briggs-Rauscher reaction, the Bray-Liebhafsky reaction and the iodine clock reaction. The concentration of products and reactants of oscillatory chemical systems can be approximated in terms of damped oscillations.