Observe the following picture a write down the chemical reaction with explanation:
The chemical reaction shown here is rusting. Rusting is a complex electrochemical reaction. Different regions on the surface of iron become anode and cathode.
First, Fe is oxidised to Fe2+ in the anode region.
Fe (s) ⟶ Fe2+(aq) + 2 e-
O2 is reduced to form water in the cathode region.
O2 (g) + 4H+(aq) + 4 e- ⟶ 2H2O (l)
When Fe2+ ions migrate from the anode region they react with water and further get oxidised to form Fe3+ ions. A redish coloured hydrated oxide is formed from Fe3+ ions. It is called rust. It collects on the surface.