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question.1. Discuss the problems associated with the use of CFCs. by.bashar & philip. Uses of CFCs incl. Refrigerants in air-conditioners and refrigerators Solvents in dry cleaning Propellants in aerosol sprays. Extensive uses of these lead to emission of gaseous CFCs into the atmosphere.

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  1. question.1 Discuss the problems associated with the use of CFCs. by.bashar & philip

  2. Uses of CFCs incl. Refrigerants in air-conditioners and refrigerators Solvents in dry cleaning Propellants in aerosol sprays Extensive uses of these lead to emission of gaseous CFCs into the atmosphere • Problems caused by CFC emission incl. • Ozone depletion • Enhanced greenhouse effect

  3. Ozone depletion • Due to the inert nature of CFCs, they do not reactive with surrounding substances in the troposphere • After time they eventually move up to the stratosphere • In the stratosphere, the CFCs photodecompose in UV radiation to produce Cl free radical CClF3(g) + UV → Cl.(g) + CF3 (g)

  4. The Cl free radical is extremely reactive as it wants to gain one electron to fill its outer shell • It reacts with an ozone molecule to produce chlorine oxide radical and O2 Cl.(g) + O3(g)→ ClO.(g) + O2(g) • Then the chlorine oxide radical reacts with an oxygen free radical to produce a chlorine free radical and O2 ClO.(g) + O.(g)→ Cl.(g) + O2(g) O3(g) + O.(g)→ 2O2(g)

  5. The ozone molecule has been destroyed and the chlorine free radical is produced again at the last stage • It then goes on to destroy thousands of ozone molecules until it eventually gets pwned • Ozone’s major role is to absorb harmful UV radiation from the sun • The destruction of ozone in the stratosphere can lead to harmful UV radiation to enter the troposphere

  6. Effects of UV radiation • Increase in skin cancer • UV can break covalent bonds in molecules such as DNA – gene mutation • Eye damage • Decrease in plant growth

  7. Enhanced greenhouse effect • Artificial emission of gases that absorb heat from the earth’s surface and reemits them in all directions, incl. back down to the earth’s surface • CFCs in the stratosphere absorb heat emitted from the earth’s surface, which prevents the heat from escaping the earth • By trapping the heat, the temperature of the earth can rise, thus climate change and global warming

  8. Effects of global warming • Change in temperature can affect the food chain • Extreme weather • Sea level rise • Et cetera.

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