Chlorofluorocarbons and the ozone layer

• How are chlorofluorocarbons linked to ozone destruction?

  They cause breakdown of ozone in the stratosphere
• What is the role of the ozone layer?

  • Absorbs ultraviolet radiation from the sun
  • Protects living organisms from excessive UV exposure
• How is ozone formed in the stratosphere?

  From oxygen radicals reacting with oxygen molecules
• What happens to ozone when it absorbs UV radiation?

  It breaks down into an oxygen radical and molecule
• Why do certain chemicals cause ozone breakdown?

  They release radicals that react with ozone
• What are chlorofluorocarbons (CFCs)?

  Stable haloalkanes that destroy ozone
• Why are CFCs stable molecules?

  High bond enthalpy of carbon to halogen bonds
• What process breaks the carbon to chlorine bond in CFCs?

  Photodissociation
• What is produced when a carbon to chlorine bond breaks?

  A chlorine radical
• What are the steps in the propagation of ozone destruction by CFCs?

  1. Chlorine radical reacts with ozone
  2. Produces oxygen molecule and chlorine monoxide radical
  3. Chlorine monoxide radical reacts with oxygen radical
  4. Produces chlorine radical and oxygen molecule
  5. Chlorine radical can repeat the cycle
• How does a chlorine radical act in ozone destruction?

  As a catalyst, regenerating itself
• What is the impact of one CFC molecule on ozone?

  It can destroy thousands of ozone molecules
• What led to the phasing out of CFCs?

  Evidence of their role in ozone destruction
• How are nitrogen oxide radicals formed?

  By lightning and from aircraft
• What are the reactions involving nitrogen oxide radicals in ozone destruction?

  1. Nitrogen monoxide radical reacts with ozone
  2. Produces nitrogen dioxide radical and oxygen molecule
  3. Nitrogen dioxide radical reacts with oxygen radical
  4. Produces nitrogen monoxide radical and oxygen molecule
  5. This forms a cycle similar to CFCs
• What is the relationship between radicals and ozone destruction?

  Radicals react with ozone, leading to its breakdown