Lecture on Freon and Its Environmental Impact

Introduction

• Freon was invented by chemists at DuPont Corporation in the 1930s.
• Needed for refrigeration as it evaporates and condenses at suitable temperatures for cooling.

Chemistry of Freon

• Natural Gas & Methane: Methane (CH₄) is not suitable for refrigeration due to its high evaporation temperature.
• Halogens: Replacing hydrogen atoms in methane with halogens (Fluorine, Chlorine) increases molecule weight, adjusting evaporation temperature.
• Chlorofluorocarbons (CFCs): Compounds formed by replacing hydrogen atoms with halogens.

Properties of Freon

• Advantages:
  • Colorless
  • Odorless
  • Non-toxic
  • Non-flammable
  • Incredibly stable

Uses of Freon

• Refrigeration: Revolutionized domestic refrigerators and air conditioning.
• Aerosol Cans: Used as a propellant due to its ability to remain liquid under pressure, then gas upon release.
• Electronics Industry: Used to clean components due to its solvent properties.

Environmental Impact

• 1970s Discovery: Chemists discovered that Freon destroys the ozone layer.
  • Chlorine atoms from Freon react with ozone, converting O₃ to O₂.
  • One chlorine atom can destroy up to 100,000 ozone molecules.

Reaction and Controversy

• DuPont's Response: Initially opposed the findings, attempted to discredit the chemists.
• Scientific Community: Grew skeptical of DuPont's resistance, further studies confirmed ozone depletion.

Effects of Ozone Depletion

• Human Health:
  • Increased UV exposure leads to sunburns, skin cancer, eye damage, immune system damage.
• Animal Health:
  • Similar effects as humans, with additional impacts on reproduction and longevity.
• Marine Life:
  • Plankton affected, risking the collapse of the oceanic nutrition system.
• Plants and Crops:
  • UV causes sunburn damage, reducing crop yields and threatening food security.

Resolution

• Montreal Protocol (1987): International agreement to phase out substances that deplete the ozone layer, including Freon.

Conclusion

• Freon, once a miracle substance, was found to have devastating long-term environmental impacts.
• The global scientific and policy response culminated in significant regulatory measures to protect the ozone layer.