Question

Which of the following free radicals is responsible for causing break down of ozone into oxygen due 10 use of,CFCs? (a) \(\mathrm{O}\) (b) \(\overrightarrow{\mathrm{Cl}}\) (c) \(\dot{\mathrm{C}} \mathrm{H}_{3}\) (d) \(\dot{\mathrm{OH}}\)

Short answer

The free radical responsible for the breakdown of ozone due to the use of CFCs is (b) \(\overrightarrow{\mathrm{Cl}}\).

Step-by-step solution

Understanding the Problem

The exercise asks to identify the free radical that causes the breakdown of ozone into oxygen due to the use of Chlorofluorocarbons (CFCs).

Recall the Role of Chlorofluorocarbons (CFCs)

Chlorofluorocarbons have been known to release chlorine atoms into the stratosphere where they catalyze the breakdown of ozone molecules into oxygen molecules.

Identifying the Correct Free Radical

Since chlorine atoms from CFCs are responsible for the ozone breakdown, the correct free radical associated with this process is the chlorine radical, which is represented as (b) \(\overrightarrow{\mathrm{Cl}}\).

Key concepts

Chlorofluorocarbons (CFCs)

Chlorofluorocarbons, commonly known as CFCs, are compounds that were once widely used in aerosol sprays, refrigerants, and foam-blowing agents. CFCs consist of chlorine, fluorine, and carbon atoms, which are stable at ground level but have damaging effects higher up in the stratosphere.

When CFCs ascend into the stratosphere, they are broken down by ultraviolet radiation from the sun, releasing chlorine atoms. These chlorine atoms are highly reactive and initiate a series of chemical reactions that lead to the destruction of ozone molecules. This process occurs as chlorine atoms react with ozone (\texttt{O\(_3\)}), converting it into oxygen gas (\texttt{O\(_2\)}), thus depleting the ozone layer.

Free Radicals

Free radicals are highly reactive, short-lived molecules or atoms that have unpaired electrons. In the context of ozone depletion, certain free radicals play a pivotal role. The most notorious is the chlorine radical, denoted by \texttt{Cl\textsuperscript{\(\bullet\)}}.

Once released, a single chlorine free radical can destroy thousands of ozone molecules before it is deactivated. It does so by participating in catalytic cycles, where it is not consumed but regenerated, allowing it to repeatedly attack ozone molecules. This destructive cycle is a prime example of how free radicals can influence environmental chemistry and has been a central part of scientific discussions about anthropogenic impacts on the atmosphere.

Ozone Layer Protection

The ozone layer serves as Earth's protective shield, absorbing harmful ultraviolet (UV) radiation from the sun. Protecting this layer is crucial for preventing increased UV exposure, which can lead to skin cancer and other health hazards for humans, as well as ecological disturbances.

To protect the ozone layer, international agreements such as the Montreal Protocol have been established to phase out the production of ozone-depleting substances, including CFCs. Alternatives to CFCs, such as hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs), although not perfect, provide less harmful options. Public awareness, scientific monitoring, and regulatory measures play a significant role in safeguarding the ozone layer for future generations.