Description of experiment
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Needed compounds:
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potassium bromate : KBrO3
sulphuric acid : H2SO4
hydrogen peroxide : H2O2
Class:
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elem=Br,O
redox
Summary:
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Potassium bromate is capable of oxidizing hydrogen peroxide, itself being
reduced to bromine.
Description:
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Dissolve some potassium bromate in dilute sulphuric acid (appr. 2 mol/l) and
add some hydrogen peroxide (appr. 10% by weight): The liquid slowly turns
yellow/orange and a gas is evolved slowly (liquid starts bubbling, like
carbonated soft drinks). The reaction takes a few minutes and immediately
after the addition of the hydrogen peroxide the liquid appears colorless for
a few seconds and then it becomes very light yellow and after that it slowly
becomes darker yellow. Finally, the liquid is yellow/orange and one can see
the bromine in the gas-mixture above the liquid clearly.