How do CFCs harm the ozone layer?

CFCs harm the ozone layer by releasing chlorine atoms which catalyse the breakdown of ozone into oxygen.

Chlorofluorocarbons (CFCs) are long-lived chemical compounds that eventually rise into the stratosphere, where they are broken apart by solar radiation, releasing chlorine atoms. These atoms are capable of catalysing the breakdown of ozone (O3) into oxygen (O2), thus depleting the ozone layer. This process is particularly concerning because one chlorine atom can destroy many ozone molecules before it is removed from the stratosphere.

The process begins when CFCs are released into the atmosphere. These compounds are stable and do not easily break down in the lower atmosphere. However, when they reach the stratosphere, they are broken down by solar radiation, releasing chlorine atoms. These atoms are extremely reactive and can catalyse a series of reactions that lead to the breakdown of ozone.

The reaction begins when a chlorine atom reacts with an ozone molecule, forming chlorine monoxide (ClO) and a molecule of oxygen. The chlorine monoxide can then react with another ozone molecule, releasing a chlorine atom and forming two molecules of oxygen. The released chlorine atom can then repeat the process, destroying more ozone molecules.

This process is particularly damaging because it is a catalytic cycle. This means that one chlorine atom can destroy many ozone molecules before it is finally removed from the stratosphere. This makes CFCs a potent threat to the ozone layer.

In summary, CFCs harm the ozone layer by releasing chlorine atoms in the stratosphere. These atoms catalyse a series of reactions that break down ozone into oxygen, depleting the ozone layer. This process is a catalytic cycle, meaning that a single chlorine atom can destroy many ozone molecules, making CFCs a significant threat to the ozone layer.