Answer:
Step-by-step explanation:
The two reactions involved in the rusting of iron are:
Oxidation: Fe -> Fe2+ + 2e- (iron loses electrons, is oxidized)
Reduction: O2 + 4e- + 4H+ -> 2H2O (oxygen gains electrons, is reduced)
In the first reaction, iron loses two electrons to become ferrous ion (Fe2+), so this is an oxidation reaction.
In the second reaction, oxygen gains four electrons and combines with four hydrogen ions (protons) to form two water molecules. Since oxygen is gaining electrons, this is a reduction reaction.
Oxidation and reduction always occur together - for one substance to be oxidized, another must be reduced. In the rusting of iron, iron is oxidized to ferrous ion which in turn reduces oxygen to form water.