Ozone Dr Ron Rusay Spring 2004 Copyright 2004

Ozone Dr. Ron Rusay Spring 2004 © Copyright 2004 R. J. Rusay

Sun worship? Or getting their vitamins? Vitamin D? ; How’s your mood today?

Electromagnetic Radiation: Light, Energy, Sunburn

Electromagnetic Radiation: Light, Energy, Sunburn

http: //chemistry. beloit. edu/Stars/EMSpectrum/index. html http: //mc 2. CChem. Berkeley. EDU/Java/

Ozone, sunscreen and SPF. http: //chemistry. beloit. edu/Stars/EMSpectrum/index. html

Satellite Images of the Antarctic Ozone Hole

Northern Hemisphere

South Pole: Mean Level (October)

The Size of Ozone “Hole” over Antarctica

Remember, O 2 and N 2 do not absorb infrared radiation. However O 2 does absorb ultraviolet radiation.

• O 2 absorbs ultra violet radiation at lower . • O 3 also absorbs ultraviolet radiation, but at higher wavelength.

Ultraviolet radiation is one of the most potent mutagens, I. e. , It causes mutations in DNA which is believed to be linked to a number of illnesses including skin cancer, malignant melanoma, and cataracts.

A normal eye.

An eye with a cataract.

The ozone cycle: A delicate balance (equilibrium).

Ozone Kinetics Stratospheric ozone is very important. It absorbs short-wavelength (~ 3 x 10 -7 m) ultraviolet (UV) radiation from the sun which is one of the strongest mutagens. O 2 (g) + O(g) O 3 (g) [formation] O 3 (g) + O(g) O 2 (g) O 3 (g) UV photon UVA UV photon UVB or UVC 2 O(g) O 2 (g) + O(g) 2 O 2 (g) [breakdown]

Ozone Kinetics: Catalysis UV photon CF 2 Cl 2 (g) . CF Cl +. Cl UVA 2 (g)

CFCs & Depletion of Ozone Freon -12 CF 2 Cl 2 (g) . O 3 (g) + Cl(g) . Cl. O (g) + O(g) O 3 (g) + O(g) UV photon UVA . CF Cl +. Cl 2 (g) . Cl. O + O. Cl + O (g) (g) 2 O 2 (g) The • represents an unpaired electron, resulting from homolytic bond breaking, and the resultant molecules are respectively called a “free radical”. They are very reactive.

• Do you like strawberries? • Should methyl bromide be banned?