Give four examples of heterogeneous catalysis.

Explanation

(i) Oxidation of `SO_2` into `SO_3` in the presence of finely divided platinum.
`2SO_2 (g) + O_2 (g) overset(Pt)to 2SO_3 (g)`
(ii) Combination of `H_2` and `N_2` to form `NH_3` in the presence of finely divided iron.
`N_2 (g) + 3H_2 (g) overset(Fe)to 2NH_3 (g)`
(iii) Oxidation of ammonia to nitric oxide in the presence of platinum gauze.
`4NH_3 (g) + 5O_2 (g) overset(Pt (s) "Heat")to4NO(g) + 6H_2 O (g)`
Hydrogenation of vegetable oils in the presence of finely divided nickel as catalyst.
Vegetable oil (l) + `H_2 (g) overset(Ni (s))to ` Vegetable ghee (s)