Chlorofluorocarbons (CFCs) :: essays research papers fc

Chloroflourocarbons Chloroflourocarbons were discovered in the 1920's by Thomas Midgley, an organic chemist at General Motors Corporation. He was looking for inert, non- toxic, non-flammable compounds with low boiling points that could be used as refrigerants. He found what he was looking for in the form of two compounds: dichlorodifluoromethane (CFC-12) and trichloromonoflouromethane (CFC-11). In both compounds, different amounts of chlorine and fluorine are combined with methane, which is a combination of carbon and hydrogen. These two CFCs were eventually manufactured by E.I. du Pont de Nemours and company, and, under the trade name â€Å"freon,† constituted 15% of the market for refrigerator gases.   Ã‚  Ã‚  Ã‚  Ã‚  CFCs were the perfect answer for cooling refrigerators and air conditioners. They were easily turned into liquid at room temperature with application of just a small amount of pressure, and they could easily then be turned back into gas. CFCs were completely inert and not poisonous to humans. They became ideal solvents for industrial solutions and hospital sterilants. Another use found for them was to blow liquid plastic into various kinds of foams. In the 1930's, household insecticides were bulky and hard to use, so CFCs were created because they could be kept in liquid form and in an only slightly pressurized can. Thus, in 1947, the spray can was born, selling millions of cans each year. Insecticides were only the first application for CFC spray cans. They soon employed a number of products from deodorant to hair spray. In 1954, 188 million cans were sold in the U.S. alone, and four years later, the number jumped to 500 million. CFC filled cans were so popular that, by 1968, 2.3 billion spray cans were sold in America. The hopes of a seemingly perfect refrigerant were diminished in the late 1960's when scientists studied the decomposition of CFCs in the atmosphere. What they found was startling. Chlorine atoms are released as the CFCs decompose, thus destroying the Ozone (O3) atoms in the high stratosphere. It became clear that human usage of CF2Cl2 and CFCl3, and similar chemicals were causing a negative impact on the chemistry of the high altitude air.   Ã‚  Ã‚  Ã‚  Ã‚  When CFCs and other ozone-degrading chemicals are emitted, they mix with the atmosphere and eventually rise to the stratosphere. CFCs themselves do not actually effect the ozone, but their decay products do. After they photolyzed, the chlorine eventually ends up as â€Å"reservoir species† - they do not themselves react with ozone- such as Hydrogen Chloride, HCL, or Chlorine Nitrate, ClONO2. These than further decompose into ozone hurting substances. The simplest is as follows: (How do CFCs Destroy the Ozone) Cl + O3 -----> ClO + O2   Ã‚  Ã‚  Ã‚  Ã‚  ClO + O