Chlorofluorocarbons CFCs are organic compounds containing carbon, chlorine, and fluorine atoms. They were widely used as refrigerants, propellants, and solvents in the past. However, it was discovered that CFCs have a detrimental effect on the ozone layer in the stratosphere, leading to the ozone depletion problem.The mechanism by which CFCs react with ozone in the stratosphere can be described in the following steps:1. Photodissociation of CFCs: When CFCs reach the stratosphere, they are exposed to high-energy ultraviolet UV radiation from the sun. This UV radiation causes the CFC molecules to break apart, releasing highly reactive chlorine atoms. For example, when CFC-12 CCl2F2 undergoes photodissociation, it forms a chlorine atom and a chlorofluoromethane radical: CCl2F2 + UV light Cl + CClF22. Reaction of chlorine atoms with ozone: The reactive chlorine atoms Cl released in the previous step can then react with ozone O3 molecules, forming chlorine monoxide ClO and molecular oxygen O2 : Cl + O3 ClO + O23. Reaction of chlorine monoxide with atomic oxygen: Chlorine monoxide ClO can further react with atomic oxygen O to regenerate the chlorine atom Cl and form molecular oxygen O2 : ClO + O Cl + O24. Catalytic ozone destruction cycle: The regenerated chlorine atom Cl can then react with another ozone molecule, repeating the process and destroying more ozone molecules. This is a catalytic cycle, as the chlorine atom is not consumed in the overall reaction and can continue to destroy ozone molecules.The consequences of this reaction on the ozone layer are significant:1. Ozone depletion: The catalytic destruction of ozone by CFCs leads to a decrease in the concentration of ozone in the stratosphere. This is a major environmental concern, as the ozone layer plays a crucial role in protecting life on Earth from harmful UV radiation.2. Increased UV radiation: With a depleted ozone layer, more UV radiation reaches the Earth's surface, leading to an increased risk of skin cancer, cataracts, and other health issues in humans. It also has harmful effects on ecosystems, including reduced crop yields and damage to aquatic life.3. Climate change: CFCs are potent greenhouse gases, contributing to global warming by trapping heat in the Earth's atmosphere. Although the production and use of CFCs have been significantly reduced due to international agreements like the Montreal Protocol, their long atmospheric lifetime means that they will continue to impact the ozone layer and climate for many years to come.