Connecting Gases to Stratospheric Ozone Depletion

Learning Resources

Summarize the process in which CFC and HCFC molecules are broken down by photochemical reactions to release chlorine atoms.
Associate the free radical catalytic cycles that chlorine atoms take part in with the resulting ozone depletion and the Chapman cycle.

Key ideas 1-3 provide useful background information on several properties of gases and the atmosphere such as: the ideal gas law, kinetic molecular theory, and atmospheric composition and layer temperatures. Key idea 4, page 7 includes information on the specific example of CFCs and their role in ozone depletion.

This learning tool visualizes the effect of different types of electromagnetic radiation on a CFC molecule. Use the slider at the top to select different wavelengths of radiation and notice their effects on the behavior of the molecule. For example, when a CFC is in the stratosphere, it absorbs UV radiation. When a photon of UV light hits the molecule, the C-Cl bond breaks and releases a chlorine atom into the atmosphere, which is visually represented in the learning tool. This chlorine free radical takes part in the destruction of ozone molecules by acting as a catalyst.

This interactive learning resource walks through the history of refrigerants and the factors used to evaluate them throughout the eras. Students can use this tool along with the attached lesson to further explore the applications of gases and ozone depleting substances such as CFCs and HCFCs.