okay, well im in 8th grade and im doing an extra credit report on the ozone layer.. its worth 5 grade points. so here it is.. and please just help with anything on it i will take advice.
The Ozone layer is formed in the upper atmosphere when light from the Sun breaks apart oxygen molecules. Some of this monatomic¹ oxygen combines with nitrogen molecules and some with oxygen molecules to make ozone. However most combine with other monatomic oxygen. Some of the nitrogen+oxygen molecules can catch lower energy light to make ozone. As the density of the atmosphere increases, this happens more and more often, until there is little or no UV-C available to break apart more oxygen molecules.
The decrease of stratospheric ozone was first reported in 1974 and its decrease was linked to the presence of manmade compounds in the atmosphere – the most damaging of which is the class of compounds know as Chlorofluorocarbons or CFCs. CFCs are the major category of man-made halocarbons. Halocarbons are formed when halogen gases such as fluorine, chlorine and bromine become attached to carbon. The smaller halocarbons turn into a gas quite easily and are the prime suspects in ozone depletion.
CFCs are used in industry in a variety of ways. They were discovered in the 1930s by American chemist Thomas Midgley and were used in refrigerators, home insulation, plastic foam, and throwaway food containers.
The non-reactivity of CFC’s, allows them to drift for years in the environment until they eventually reach the stratosphere. High in the stratosphere, intense UV solar radiation splits the chlorine molecules off the CFC’s. These then attract one of the three oxygen atoms in the ozone molecule (O3) – destroying the ozone by turning it into oxygen. A single chlorine atom can destroy over 100,000 molecules of ozone in this way.
CFCs vary widely in their stability and in how effective they are at destroying ozone. Unfortunately, most of them will persist in the atmosphere for 50-200 years. Although many countries have moved to reduce the use of CFCs, this long life of CFCs means that the impact of chlorofluorocarbons currently in the atmosphere will continue well into the next century.
Some ways to prevent Ozone layer destruction are to handle and dispose of CFC’s properly, encourage growth of plants that produce oxygen, discourage deforestation, decrease or control the amount of hot water vapor being released into the atmosphere, use products with CFC’s in them less often, and discouraging the burning of plastic.
¹ – Monatomic- having one atom in the molecule
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so that ends the report, what did you think?
Thanks,
Bullfrog
Overall you report is quite complete and well written.
A few important things I can see that you might want to add:
- there is a ban on the use of CFCs since more than twenty years. After negotiation of an international treaty (the Montreal Protocol), CFC production was sharply limited beginning in 1987 and phased out completely by 1996.
- you don’t talk at all about the ozone hole above the Antartic. It’s the same phenomenon of course, but enhanced by the extreme cold, that in winter favorizes the creation of polar stratospheric clouds (PSCs).
These PSCs are clouds of nitric acid and ice. The cloud particles act both as reaction surface for the depletion reaction and as catalyzer via the formation of hydrochloric acid (HCl) and chlorine nitrate (ClONO2). When spring and the Sun arrives, free Cl and ClO radicals are formed, which attack the ozone. The PSCs therefore act to concentrate the presence of radicals in the spring above the poles.
- the reason why ozone depletion is harmful.
Lastly: a good report quotes its sources.