- Half-reaction
A half reaction is either the oxidation or reduction reaction component of a
redox reaction . A half reaction is obtained by considering the change inoxidation state s of individual substances involved in the redox reaction.Consider the reaction below:
:Cl2 + 2Fe2+ → 2Cl− + 2Fe3+
The two elements involved,
iron andchlorine , each change oxidation state; iron from 2+ to 3+, chlorine from 0 to 1−. There are then effectively two "half"-reactions occurring. These changes can be represented in formulas by inserting appropriateelectron s into each half-reaction::Fe2+ → Fe3+ + e− :Cl2 + 2e− → 2Cl−
In the same way given two half-reactions it is possible, with knowledge of appropriate
electrode potential s, to arrive at the full (original) reaction.See also
*
Electrode potential
*Standard electrode potential (data page)
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