Environmental chemistry

1. Environmental chemistry E. 9 ozone

2. ozone Explain the dependence of O2 and O3 dissociation on the wavelength of light. Describe the mechanism in the catalysis of O3 depletion by CFCs and NOx. Outline the reasons for greater ozone depletion in polar regions.

3. ozone depletionhttp://www.theozonehole.com/

4. photodissociation photodissociation of O2 photodissociation of O3

5. sample calculation

6. sample calculation

7. Catalytic depletion CFCs

8. Catalytic depletion by NO

9. Catalytic depletion by NO2 • NO2  NO + O2 • NO + O3  NO2 + O2 • NO2 + O NO + O2 • Net: O + O3  2O2

10. ozone in october in antarctica

12. greater ozone depletion in polar regions very cold winter temperatures over the polar regions ice crystals form in the stratosphere and act as heterogeneous catalysts for reactions which produce chlorine oxides (e.g. HOCl) and Cl2 from CFCs. during winter time a huge reservoir of HOCl and Cl2 molecules builds up until spring arrives. spring brings UV light which causes chlorine free radicals to split from the HOCl or Cl2 molecules. greater catalytic depletion of the ozone in the polar regions. UV also melts the ice crystals and stops the formation of HOCl and Cl2 slowing down this process.