| Reduction-oxidation
(redox) reactions are chemical reactions in which
reactants experience a change in oxidation number (which
means these reactants either gain or lose electrons).
If an atom in a reactant gained electrons (its
oxidation # decreased) it
was reduced.
If an atom in a reactant lost electrons (its
oxidation # increased) it
was oxidized.
Since chemical reactions don't make or destroy
electrons, oxidation and reduction must occur at the
same time. As one reactant is oxidized, the electrons it
loses are accepted by another reactant which is reduced.
Cu2+ + Zn --> Cu + Zn2+
The Cu2+ is reduced
(ox. # decreased).
The Zn is oxidized (ox. #
increased).
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