Define and discuss the function of a catalyst in a chemical reaction. Show an example of the conversion of cis-2-butene into trans-2-butene using a halogen atom. Show step by step how the catalyst is involved in speeding up the chemical reaction. Use print outs to aid the demonstration. Also discuss the effect of ozone on the environment. Determine how oxygen is converted to ozone by halogen carbonates. Discuss the harmful effects of UV radiation on skin and eyes caused by decreases in the ozone layer concentration due to chemicals like freon. Show how the freon decreases the ozone layer by catalyzing the decomposition reaction.