In an oxidation-reduction reaction, what substance is reduced always?

1 Answer
Feb 5, 2016

The OXIDANT is always reduced in a redox reaction.

Explanation:

Formally, a species that gains electrons is reduced, and a species that loses electrons is oxidized. When oxygen (typically) is reacted with a hydrocarbon fuel, the oxygen is formally reduced to #CO_2#, in which the oxygen number of #O# is #-II#, REDUCED from the zerovalent elemental state. On the other hand, the #C# has been oxidized from #-II# or so to #+IV#.