Project: examining the use of certain gases as propěllants
the opening chapters of this unit discussed the properties of gases. this activity will introduce you to sources of gases that
sources of gases that
are currently considered "hot topics" in environmental chemistry. it also will demonstrate the use of chemical equations in
real world settings.
uations in
the mid-1970s brought a big controversy in the scientific world concerning the use and misuse of propellants in aerosol
dispensers. some scientists felt that aerosol chemicals sprayed into the atmosphere would destroy the ozone (o3) layer
enveloping the earth.
when a typical chlorofluorocarbon (cfc), such as freon (cc13f), reaches the height of the ozone layer, the energy of
ultraviolet rays from the sun can cleave individual chlorine atoms from the molecule. these highly reactive atoms are then
able to react with the ozone (o3) found in abundance in the stratosphere. the following chemical reactions characterize the
ozone destroying process:
ci + o3 - cio + o2 followed by cio +
ci+ o2
two things should be noted here. first, in cleaving the first ozone molecule, a very reactive atomic oxygen is produced
which immediately reacts with the hypochlorite product of the first reaction. this releases the original reactive chlorine,
which is then free to destroy another ozone moleculel so the cycle continues.
do further research on this photo-reactive process and then write a 500 word essay on the pros and cons of the
controversy of using chlorofluorocarbons as aerosol propellants. include and cite recent scientific findings and explain why
the ozone layer is so critical to our existence.