Mechanisms

Question 1

Explain the process of Free Radical Substitution

Answer 1

In Initiation, the breaking of the halogen bond which uses UV light

Propagation - Cl• + CH4 –> HCl + •CH3
•CH3 + Cl2 –> CH3Cl + Cl•

Termination - Cl• + Cl• –> Cl2
Cl• + •CH3 –> CH3Cl
•CH3 + • CH3 –> C2H6

Question 2

Explain how CFCs breakdown Ozone

Answer 2

Initiation -. CCl3F + hv –> •CCl2F + Cl•

Propagation -
Cl• + O3 –> O2 + ClO•
ClO• + O3 –> 2O2 + Cl•
Termination -
Cl• + Cl• –> Cl2

Overall:. 2O3(g) —> 3O2(g)

Question 3

Why are CFCs no longer used

Answer 3

Despite being unstable, unreactive and not toxic and were used in fridges and deodorants but they damage the ozone.

RISKS OUTWEIGHED THE BENEFITS

HFCs (Hydroflurocarbons) are safer as they don’t have chlorine.