Bray–Liebhafsky reaction

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The Bray–Liebhafsky reaction is a

anion of iodic acid, in the catalytic conversion of hydrogen peroxide to oxygen and water
by the iodate. He observed that the concentration of iodine molecules oscillated periodically and that hydrogen peroxide was consumed during the reaction.

An increase in temperature reduces the cycle in the range of hours. This oscillating reaction consisting of

free radical on non-radical steps was investigated further by his student Herman A. Liebhafsky,[2]
hence the name Bray–Liebhafsky reaction. During this period, most chemists rejected the phenomenon and tried to explain the oscillation by invoking heterogeneous impurities.

A fundamental property of this system is that hydrogen peroxide has a

:

5 H2O2 + I2 → 2 IO
3
+ 2 H+ + 4 H2O

and the reduction of iodate back to iodine:

5 H2O2 + 2 IO
3
+ 2 H+ → I2 + 5 O2 + 6 H2O

Between these two reactions the system oscillates causing a concentration jump of the iodide and the oxygen production. The net reaction is:

2 H2O2 → 2 H2O + O2

necessitating a

catalyst
and IO
3
.

References

Further reading