The oxidation-reduction reaction contains a reductant and an oxidant (oxidizing agent).
An oxidizing agent, or oxidant, gains electrons and is reduced in a chemical reaction. Also known as the electron acceptor, the oxidizing agent is normally in one of its higher possible oxidation states because it will gain electrons and be reduced.
A reducing agent (also called a reductant or reducer) is an element (such as calcium) or compound that loses (or "donates") an electron to another chemical species in a redox chemical reaction.
For the reaction:
<em>2Na + S → Na₂S.</em>
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Na is oxidized to Na⁺ in (Na₂S) (loses 1 electron). "reducing agent".
S is reduced to S²⁻ in (Na₂S) (gains 2 electrons). "oxidizing agent".
