Write the chemical equations for all the steps involved in the rusting of iron. Give any one method to prevent rusting of iron.

Explanation

At a particular spot of the iron object, oxidation takes place. That spot acts as anode. The reaction at anode can be written as:
`2Fe (s) to 2Fe^(2+) (aq) + 4e^(-)`.........(i)
Electrons released at anode move through the metal to another spot and reduce oxygen in the presence of `H^+`.
This spot acts as cathode. The reaction at cathode can be represented as:
`O_2 (8) + 4H^(+) (aq) + 4^(e-) to 2H_2O(l)`.........
(ii) The overall reaction by combining (i) and (ii) `2Fe (s) + O_2 (g) + 4H^(+ )(aq) to 2Fe^(2+) (aq) + 2H_2O` (l)
The ferrous ions are further oxidised to ferric ions which combine with water to form `Fe_(2)O_(3).xH_(2)O` which is the formula of rust.
Prevention of rusting : Iron can be prevented from rusting by galvanisation which involves coating iron with zinc. Zinc being more reactive than iron gets oxidised first and thus prevents iron from rusting.