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Training programme to help develop my performance in rugby at the position of flanker.

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Introduction

CFCs

INTRODUCTION:

The invention of Chlorofluorocarbons in the late 1920s and early 1930s stemmed from the call for safer alternatives to the sulfur dioxide and ammonia refrigerants used at the time. Refrigerators in the late 1800s and early 1900s used the toxic gases, ammonia (NH3), methyl chloride (CH3Cl), and sulfur dioxide (SO2), as refrigerants. After a series of fatal accidents in the 1920s when methyl chloride leaked out of refrigerators, a search for a less toxic replacement begun as a collaborative effort of three American corporations- Frigidaire, General Motors, and Du Pont. Thomas Midgley, Jr. of General Motors first synthesized CFCs in 1928, as safer chemicals for refrigerators used in large commercial applications. Chlorofluorocarbons or (CFCs) as they are generally known are nontoxic, nonflammable chemicals containing atoms of carbon, chlorine, and fluorine and sometimes hydrogen. CFCs are classified as halocarbons, a class of compounds that contain atoms of carbon and halogen

USES AND REASONS WHY:

They are used in the manufacture of aerosol sprays, blowing agents for foams, packing materials, as solvents, propellants for spray cans, electronic cleaning solvents and as refrigerants. CFCs are suitable because they are non-toxic, non-flammable, non corrosive and non-reactive with other chemical compounds.

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Middle

Equation one: CF 2 Cl 2 ==> CF 2 Cl + Cl.

Equation two: Cl + O3 ==> ClO + O2                  Equation three: ClO + O ==> Cl + O2

The two above reactions result in: O3 + O ===> 2O2

Chlorine (Cl) is initially removed by reaction with ozone (O3) to form chlorine monoxide (ClO) in the second equation, The chlorine is regenerated through reaction of ClO with an oxygen atom (O) in the third equation. The net result of the two reactions is the depletion of ozone and atomic oxygen into oxygen molecules. A loss of stratospheric ozone results in more harmful UV-B radiation reaching the Earth's surface which is armful to plants and animals.100, 000 molecules of ozone can be destroyed per chlorine atom.

As well as depleting ozone, CFCs also act as greenhouse gases. With more greenhouse gases in the atmosphere, the natural greenhouse effect is being enhanced artificially, and this could bring about global warming. Increased concentrations of greenhouse gases in the atmosphere enhance the earth's natural greenhouse effect by trapping a greater proportion of the infrared energy (or radiation) that is leaving the Earth. This is called climate forcing and causes a temperature rise at the Earth's surface.

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Conclusion

CFCs concentration in the Northern and Southern Hemisphereimage03.png

BIBLIOGRAPHY

  • www. Encyclopedia. Com
  • www. Greennature. Com
  • Chemistry in context text book
  • Green house affect leaflet from  Library
  • www. cszinc. com/industrial
  • www. Medlina .com

BY Shirley Namubiru

CHLOROFLUOROCARBON

image04.png

BY SHIRLEY NAMUBIRU

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