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Chemistry LibreTexts

Oscillating Clock

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  • The Briggs-Rauscher reaction is an oscillating reaction like the Belousov-Zhabotinsk reaction.



    The essential features of the system depend on two key processes, each involving many reactions working together:

    • A ("non-radical process"): The slow consumption of free iodine by the malonic acid substrate in the presence of iodate. This process involves the intermediate production of iodide ion.
    • B ("radical process"): A fast process involving manganese and free radical intermediates, which converts hydrogen peroxide and iodate to free iodine and oxygen. This process also can consume iodide up to a limiting rate.

    IO3- + 2 H2O2 + CH2(CO2H)2 + H+ -> ICH(CO2H)2 + 2 O2 + 3 H2O

    The striking visual demonstration occurs by the addition of a starch indicator.


    Do not drink this.

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