Ozone Layer

             O + O2 03.
             This is the formation of ozone from a oxygen molecule and a oxygen atom. .
             The rate of this reaction can be examined using a method called flash photolysis. What happens with this is a short pulse of light produced from a laser is used to produce Oxygen atoms from Oxygen molecules. The Oxygen atoms then react quickly with some of the remaining oxygen molecules, and their concentration can be measured using spectroscopic instruments at different times after the flash. An expression is then used to find the rate of reaction:.
             Rate of reaction=k(O2)(O).
             K=rate constant.
             (O2)(O)=concentrations of oxygen atoms and molecules.
             The rate constant depends on the temperature and pressure of which the reaction is happening and determine how fast it is going.
             Meteorology is the study of air movement in the atmosphere. This helps us understand the chemistry in the stratosphere as it tells us what is likely to be found there and what height the ozone is found at. It also allows us to make predictions.
             In 1972, James LoverLock found a way of detecting CFC's in the Troposphere. He found out that they would accumulate around the atmosphere because they were so stable. Then, Sherwood Rowland found that CFCs will absorb the high energy ultra-violet radiation and release Cl
             • in the stratosphere. in 1987, Farman discovered the ozone hole by measurement. Scientist also flew over the hole and found that there is a drop in Ozone where ClO
             • concentration is highest.
             In natural circumstances, Ozone is destroyed and created by the following free radical reactions. Oxygen is split up:.
             O2 + hv à O
             • + O
             • .
             ( l < 242nm UV) (1).
             Then they form ozone by:.
             O
             • + O2 à O3 (2).
             and destroyed by: .
             O
             • + O3 à 2O2 (3).
             O3 + hv à O2 + O2 .
             ( 297nm < l < 214nm UV) (4).
             .
             4 is responsible for the sun screening effect of Ozone. A steady state is established between the rate of which Ozone is destroyed and formed.