KCET 2017 Chemistry Solved Paper

Homolytic bond fission takes place in free radical chlorination of methane.
The reaction occurs by a free radical mechanism which involves the following 3 steps:
Step 1: Chain initiation
Step 2: Chain propagation

CH4

Methane

+

Cl hv –––––>

Chlorine‌free‌radical

CH3+HCl
CH3+Cl−Cl

hv

→

CH3−Cl+Cl
CH3Cl+Cl→CH2Cl+HCl
CH2Cl+Cl−Cl→CH2Cl2+Cl
Step 3: Chain termination
Cl+Cl→Cl−Cl
CH3+CH3⟶

CH3−CH3

(Ethane)

CH3+Cl⟶CH3−Cl