CFCs and ozone

• What is the chemical formula for ozone?

  O3
• How does ozone protect life on Earth?

  It absorbs UVB radiation from the Sun
• What harmful effects does UVB radiation cause?

  Sunburn, genetic damage, and cancer
• What is the significance of the ozone layer's location?

  It is found within the stratosphere
• What trend was observed in the ozone layer from 1979 to 2008?

  The hole in the ozone layer increased in size
• What are CFCs and their uses?

  They are chlorofluorocarbons used as solvents
• Why are CFCs stable until they reach the upper atmosphere?

  Due to the strength of the carbon halogen bond
• What happens to CFCs in the upper atmosphere?

  They break down and form radicals
• How do halogen radicals affect ozone?

  They react with ozone to deplete it
• What is the overall effect of the reactions involving ozone and radicals?

  Ozone is converted into oxygen gas
• Why are CFCs still entering the atmosphere today?

  They have a long life and are still used
• What alternatives are scientists investigating to CFCs?

  Alternative coolants for refrigeration systems
• What actions have governments taken regarding CFCs?

  They have legislated against their use
• What are the functions and properties of ozone?

  • Absorbs UVB radiation
  • Protects life on Earth
  • Chemical formula: O₃
• What are the effects of CFCs on the ozone layer?

  • CFCs break down in the upper atmosphere
  • Form halogen radicals
  • Radicals react with ozone, depleting it
• What are the characteristics of CFCs that made them popular?

  • Non-toxic
  • Volatile
  • Non-flammable
  • Stable due to strong carbon halogen bonds
• What is the significance of the images from NASA regarding the ozone layer?

  • Show the growing hole in the ozone layer
  • Compare images from 1979 and 2008
  • Indicate the increase in ozone depletion
• What are HFCs


  hydrofluorocarbons
• Why are HFCs less harmful to the ozone layer than CFC’s?

  • HFCs do not contain chlorine, which is the main ozone-depleting component in CFCs. CF bond is stronger than CCl bond
• What are the 2 equations when chlorine free radicals react with ozone ?

  1. Cl . + O3 > ClO. + O2
  2. ClO. + O3 > 2O2 +Cl.
• The decomposition equation when a catalyst (could be anything like NO or Cl) decomposes ozone to oxygen

  2O3 —> 3O2