Final answer:
The source of chlorine in the stratosphere is confirmed to be chlorofluorocarbons (CFCs), which decompose under UV radiation releasing chlorine atoms that catalytically destroy ozone molecules.
Step-by-step explanation:
We determine that the chlorine in the stratosphere is coming from chlorofluorocarbons (CFCs) through the understanding of the chemical kinetics of CFC decomposition. Once CFCs reach the stratosphere, they are broken down by ultraviolet (UV) radiation, releasing chlorine atoms. These chlorine atoms are highly reactive and initiate a catalytic cycle of ozone depletion, resulting in a net removal of ozone (O3) molecules from the stratosphere.
This process can be represented by the reactions:
- Cl + O3 → ClO + O2
- ClO + O → Cl + O2
The persistent nature of CFCs allows them to diffuse to great altitudes in the atmosphere before they decompose, thus contributing to ozone depletion over a long period. A single chlorine atom can destroy thousands of ozone molecules because it acts as a catalyst that is not consumed in the reaction.
It continues the cycle of destroying ozone, thereby resulting in increased UV radiation reaching the Earth's surface. Monitoring of the atmosphere and analysis of these decomposition reactions confirm that CFCs are the primary source of chlorine in the stratosphere responsible for ozone depletion.