C6e Ozone Layer Depletion

Folks this hasn't come up that much in the past however it would be daft not to look over this at least.

CFC's

• Stands for chlorofluorocarbons - e.g. CClF3
• Are chemically inert and so were used a lot for aerosol propellants and refrigerants
• However they have found that CFC's cause depletion of ozone layer - thats why now banned in may countries

Depletion of Ozone layer

• Ozone destroyed by a chain reaction involving free redicals
• Free radicals formed when a covalent bond breaks evenly:  Cl2 --> .Cl  + .Cl  
• As its a chain reaction a small number of free radicals will react with many ozone molecules

Stages of destruction of ozone are: 
1) UV light splits CFC to form chlorine free radicals: CClF3 --> .Cl  + .CF3 
2) Chlorine free radicals react with ozone (O3) to make more radicals: .Cl  + O3 --> .ClO  + O2

3) This free radical then takes part in more reactions which also make more free radicals - a chain reaction!!

Overall reaction: 2 O3 --> 3 O2      - This therefore reduces ozone levels and allows harmful UV to reach us.

CFC's only removed slowly from stratosphere - so even though they're banned it will take many years for them to fully disappear.