How many ozone molecules can one chlorine atom potentially prevent from forming?

• A. A few
• B. Hundreds
• C. Thousands
• D. Tens of thousands

Answer: (D)

One chlorine atom has the potential to prevent the formation of tens of thousands of ozone molecules due to its ability to catalyze reactions in the stratosphere. When chlorine is released into the atmosphere, often from the breakdown of chlorofluorocarbons (CFCs) and other ozone-depleting substances (ODS), it can participate in a series of reactions that lead to the destruction of ozone (O₃).

The critical point here is that a single chlorine atom can react multiple times before it is removed from the atmosphere. For example, one chlorine atom can decompose one ozone molecule into oxygen (O₂) and, in the process, regenerate itself to attack more ozone molecules. Estimates indicate that a single chlorine atom can ultimately lead to the breakdown of approximately 100,000 ozone molecules through this catalytic cycle. This high number highlights the potency of chlorine in depleting ozone, making it a significant environmental concern.