halogenoalkanes and the environment

• What are chlorofluorocarbons (CFCs)?

  Stable halogenoalkanes containing carbon, chlorine, and fluorine
• What is a key feature of CFCs regarding hydrogen atoms?

  They contain no C-H bonds
• What are the industrial and domestic uses of CFCs?

  • Refrigerants
  • Propellants
  • Solvents
• Why were CFCs widely used before the late 1980s?

  Due to their high stability and low toxicity
• What is the result of the strong carbon-halogen bonds in CFCs?

  High stability of CFCs
• What role does ozone (O3) play in the atmosphere?

  It absorbs harmful ultraviolet (UV) radiation
• How do CFCs reach the ozone layer?

  They survive long enough in the atmosphere
• What happens to CFCs when they are exposed to high-energy UV radiation?

  Carbon-halogen bonds break, releasing chlorine radicals
• What is the effect of chlorine radicals on ozone?

  They initiate a chain reaction that depletes ozone
• What is the overall reaction that describes ozone depletion by chlorine radicals?

  2O3 ➔ 3O2
• How many ozone molecules can a single chlorine radical destroy?

  More than 10,000 ozone molecules
• What was the global response to the environmental damage caused by CFCs?

  • 1989 Montreal Protocol imposed a global ban
  • CFC production banned by 2000
  • Limited use in specific applications
• What are hydrofluorocarbons (HFCs) and their environmental impact?

  They do not harm ozone but are greenhouse gases
• What are hydrocarbons in relation to CFC alternatives?

  They decompose rapidly but are flammable
• What are the strengths and weaknesses of alternatives to CFCs?

  Strengths:

  • Less harmful to the environment than CFCs
  • Safer for ozone layer

  
  

  Weaknesses:

  • HFCs are greenhouse gases
  • Hydrocarbons are flammable
• What efforts are being made regarding CFC alternatives?

  Continuous improvement and monitoring of ozone recovery