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Freon |
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Freon (frē`ŏn) [trade name], any one of a special class of chemical compounds that are used as refrigerants, aerosol propellants, and solvents. These compounds are haloalkanes, i.e., halogen derivatives of saturated hydrocarbons (see alkane alkane (ăl`kān), any of a group of aliphatic hydrocarbons whose molecules contain only single bonds (see chemical bond ). ..... Click the link for more information. ). Every Freon contains at least some fluorine in its molecule, and most contain chlorine or bromine as well. Freons are generally colorless, odorless, nontoxic, noncorrosive, nonflammable, and chemically unreactive. The most commonly used is Freon-12, or dichlorodifluoromethane (CCl2F2), which boils at −29.8°C; and is thus a gas at ordinary temperatures and pressures. It is prepared by the reaction of carbon tetrachloride with hydrogen fluoride in the presence of a catalyst. There are a number of other Freons. Some of those containing bromine in their molecules are used in fire extinguishers. See also chlorofluorocarbons Halons are organic compounds that are similar to CFCs. They contain carbon, fluorine, and bromine and may contain chlorine. Halons have been used primarily as propellants in fire extinguishers. ..... Click the link for more information. . FreonTrademark for any of several organic compounds containing fluorine (fluorocarbons) and sometimes chlorine (chlorofluorocarbons, or CFCs). Nonflammable, nontoxic, and noncorrosive, they have low boiling points, which makes them useful as refrigerants. By the mid-1970s they were in wide use in refrigeration and air conditioning systems, as blowing agents for plastic foams, as fire-extinguishing agents, and in aerosol sprays. Evidence has accumulated that decomposition of CFCs in the stratosphere destroys ozone there (see ozone layer), so most of their uses have been banned. International agreements signed by most of the industrialized countries have called for the phasing out of CFC use. Freon ™ any of a group of chemically unreactive chlorofluorocarbons used as aerosol propellants, refrigerants, and solvents How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content. |
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