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 CClF 3(g) + UV → Cl. (g) + CF 3 (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 O 2 Cl. (g) + O 3(g) → ClO. (g) + O 2(g) Then the chlorine oxide radical reacts with an oxygen free radical to produce a chlorine free radical and O 2 ClO. (g) + O. (g) → Cl. (g) + O 2(g) O 3(g) + O. (g) → 2O 2(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.