what is cfc and what it's uses
Answers
Answer:
CFC is chlorofluorocarbon gas it releases from refrigerator and cause global warming
Answer:
cfc stands for chlorofluorocarbon
Chlorofluorocarbons (CFCs) are nontoxic, nonflammable chemicals containing atoms of carbon, chlorine, and fluorine. They are used in the manufacture of aerosol sprays, blowing agents for foams and packing materials, as solvents, and as refrigerants. CFCs are classified as halocarbons, a class of compounds that contain atoms of carbon and halogen atoms. Individual CFC molecules are labeled with a unique numbering system. For example, the CFC number of 11 indicates the number of atoms of carbon, hydrogen, fluorine, and chlorine (e.g. CCl3F as CFC-11). The best way to remember the system is the "rule of 90" or add 90 to the CFC number where the first digit is the number of carbon atoms (C), the second digit is the number of hydrogen atoms (H), and the third digit is number of the fluorine atoms (F). The total number of chlorine atoms (Cl) are calculated by the expression: Cl = 2(C+1) - H - F. In the example CFC-11 has one carbon, no hydrogen, one fluorine, and therefore 3 chlorine atoms.
The demand for the CFCs was accomodated by recycling, and reuse of existing stocks of CFCs and by the use of substitutes. Some applications, for example degreasing of metals and cleaning solvents for circuit boards, that once used CFCs now use halocarbon-free fluids, water (sometimes as steam), and diluted citric acids. Industry developed two classes of halocarbon substitutes- the hydrochlorofluorocarbons (HCFCs) and the hydrofluorocarbons (HFCs). The HCFCs include hydrogen atoms in addition to chlorine, fluorine, and carbon atoms. The advantage of using HCFCs is that the hydrogen reacts with tropospheric hydroxyl (OH), resulting in a shorter atmospheric lifetime. HCFC-22 (CHClF2) has an atmospheric lifetime of about 13 years11 and has been used in low-demand home air-conditioning and some refrigeration applications since 1975. However, HCFCs still contain chlorine which makes it possible for them to destroy ozone. The Copenhagen amendment calls for their production to be eliminated by the year 2030. The HFCs are considered one of the best substitutes for reducing stratospheric ozone loss because of their short lifetime and lack of chlorine. In the United States, HFC-134a is used in all new domestic automobile air conditioners. For example, HFC-134a is growing rapidly in 1995 at a growth rate of about 100% per year with an atmospheric lifetime of about 12 years12. (The "rule of 90" also applies for the chemical formula of HCFCs and HFCs.)
Use of the CFCs, some chlorinated solvents, and Halons should become obsolete in the next decade if the Montreal Protocol is observed by all parties and substitutes are used. The science that became the basis for the Montreal Protocol resulted in the 1995 Nobel Prize for Chemistry. The prize was awarded jointly to Professors F. S. Rowland at University of California at Irvine, M. Molina at the Massachusetts Institute of Technology, Cambridge, and Paul Crutzen at the Max-Planck-Institute for Chemistry in Mainz, Germany, for their work in atmospheric chemistry, particularly concerning the formation and decomposition of ozone (in particular, by the CFCs and oxides of nitrogen).