Explain how rusting of iron is envisaged as setting up of an electroCHMemical cell.

Explanation

Formation of carbonic acid takes place on the surface of iron.
`H_(2)O(l) + CO_(2)(g) to H_(2)CO_(3) In presence of `H^(+)` ions, oxidation of iron takes place
`Fe(S) to Fe^(2+)(aq) + 2e^(-)`
The electrons are used at other spot where reduction takes place.
`O_(2)(g) + 4H^(+) (aq) + 4e^(-) to 2H_(2)O(l)`
Overall reaction is:
`2Fe(s) + O_(2)(g) (aq) Thus, an electrochemical cell is established on the surface.