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

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. During the late 1950s and early 1960s the CFCs made possible an inexpensive solution to the desire for air conditioning in many automobiles, homes, and office buildings. Later, the growth in CFCs use took off worldwide with peak, annual sales of about a billion dollars (U.S.) and more than one million metric tons of CFCs produced. These safety characteristics, along with desirable thermal-conductivity and boiling point characteristics are the which features led to increased demand and made them ideal for all the uses listed above.

ENVIRONMENTAL IMPACT:

Whereas CFCs are safe to use in most applications and are inert in the lower atmosphere, they do undergo significant reaction in the upper atmosphere or stratosphere. In 1974, two University of California chemists, who won Nobel prizes for there work: Professor F. Sherwood Rowland and Dr. Mario Molina, showed that the CFCs could be a major source of inorganic chlorine in the stratosphere following their photolytic decomposition by UV radiation. CFCs have been associated with the accelerated depletion of ozone in the Earth's stratosphere. CFCs take part in catalytic reactions in the stratosphere. A ...