Consider the reaction of water with F2 and suggest, in terms of oxidation and reduction, which species are oxidized/reduced.
The reaction between fluorine and water can be represented as:
$2 \mathrm{~F}_{2(g)}+2 \mathrm{H}_{2} \mathrm{O}_{(t)} \longrightarrow 4 \mathrm{H}_{(a q)}^{+}+4 \mathrm{~F}_{(a q)}^{-}+\mathrm{O}_{2(g)}$
This is an example of a redox reaction as water is getting oxidized to oxygen, while fluorine is being reduced to fluoride ion.
The oxidation numbers of various species can be represented as:
Fluorine is reduced from zero to (– 1) oxidation state. A decrease in oxidation state indicates the reduction of fluorine.
Water is oxidized from (– 2) to zero oxidation state. An increase in oxidation state indicates oxidation of water.