Main Page | See live article | Alphabetical index Half reactions are obtained by considering the change in oxidation states of individual substances involved in a reduction/oxidation reaction. Consider the reaction below: (1) Cl2 + 2Fe2+ -> 2Cl- + 2Fe3+ The two elements involved, iron and chlorine, 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 appropriate electrons in to each half-reaction: (3) Fe2+ -> Fe3+ + e- (4) Cl2 + 2e- -> 2Cl- In the same way given two half-reactions it is possible, with knowledge of appropriate electrode potentials, to arrive at the full (original) reaction. See also: Electrode potential This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.