115. Give four examples of heterogeneous catalysis. 

Answer:

Heterognous catalysis :
The catalytic process in which the reactant and the catalyst are in different phase is known as heterogenous catalyst.

The examples of heterogeneous system are given below:

1. Manufacture of NH₃ from N₂ and H₂ by Haber’s process, using iron as catalyst.
${\mathrm{N}}_2\left(\mathrm{g}\right)+3{\mathrm{H}}_2\left(\mathrm{g}\right) \stackrel{\mathrm{Fe}\left(s\right)}{\to } 2{\mathrm{NH}}_3\left(g\right)$

2. Oxidation of NH₃ with O₂ using Pt as catalyst in Ostwald process.
$4{\mathrm{NH}}_3+5{\mathrm{O}}_2\underset{\mathrm{Heat}}{\overset{\mathrm{Pt}}{\to }} 4\mathrm{NO}+6{\mathrm{H}}_2\mathrm{O}$
3. Oxidation of CO in automobile exhaust by platinum catalyst.

$2\mathrm{CO}+{\mathrm{O}}_2 \stackrel{\mathrm{Pt}}{\to } 2{\mathrm{CO}}_2$
4. Hydrogenation of oils to form vegetable ghee using finely divided nickel as catalyst
$\mathrm{Oil}+{\mathrm{H}}_2 \stackrel{\mathrm{Ni}}{\to } \mathrm{Vegetable} \mathrm{ghee}$