Question

Which of the following is responsible for depletion of the ozone layer in the upper strata of the atmosphere? (a) Freons (b) Ferrocene

Short answer

Freons (a) are responsible for ozone layer depletion.

Step-by-step solution

Understanding the Question

The question asks us to identify which substance is responsible for the depletion of the ozone layer in the atmosphere. We need to understand what 'ozone depletion' entails and which chemicals are commonly associated with this environmental issue.

Identifying the Substances

We are given two options: (a) Freons and (b) Ferrocene. Freons are chlorofluorocarbons (CFCs), which have been widely used as refrigerants, propellants, and solvents. Ferrocene is an organometallic compound and not related to ozone depletion.

Researching Ozone Layer Depletion

Ozone layer depletion is primarily caused by chemicals called chlorofluorocarbons (CFCs). These chemicals release chlorine atoms in the upper atmosphere, which then react with ozone and lead to its depletion. Freons are a type of CFC.

Selecting the Correct Answer

Since Freons (option a) are a type of chlorofluorocarbon responsible for releasing chlorine into the atmosphere, they are responsible for ozone depletion. Ferrocene (option b) is not related to this process.

Key concepts

Chlorofluorocarbons (CFCs)

Chlorofluorocarbons, commonly known as CFCs, are a group of man-made chemical compounds that contain chlorine, fluorine, and carbon. Originally developed in the 1930s, CFCs were celebrated for their non-reactive and stable nature, making them ideal for use in refrigeration, air conditioning, and aerosol propellants.
However, what seemed like a benefit at the time later turned out to be a significant environmental issue. Once released into the atmosphere, CFCs can persist for an extended period due to their stable nature. They gradually rise to the stratosphere, where they come into contact with ultraviolet (UV) radiation. This radiation breaks down the CFC molecules, releasing chlorine atoms.

• These chlorine atoms act as catalysts in the chemical reaction that destroys ozone molecules.
• Just one chlorine atom can destroy up to 100,000 ozone molecules before it is deactivated.

Widespread usage of CFCs led to significant ozone layer depletion, spurring international policy changes including the Montreal Protocol, which successfully phased out many CFCs to protect the ozone layer.

Environmental Chemistry

Environmental Chemistry focuses on chemical processes that occur in natural systems and how human activities impact these systems. It is crucial in understanding phenomena like ozone layer depletion.
The field studies both natural and man-made chemicals, analyzing how they affect air, soil, and water.
The ozone layer, located in the stratosphere, plays a critical role by absorbing most of the sun's harmful ultraviolet radiation. When chemicals like CFCs reach this layer, they disrupt the natural balance.

• Environmental chemists investigate sources of pollutants and how they interact with other components in the atmosphere.
• They also develop solutions for reducing or eliminating harmful chemicals from various ecosystems.

By understanding these complex interactions, scientists can make informed decisions about laws and regulations designed to protect the environment.

Atmospheric Chemistry

Atmospheric Chemistry is concerned with the chemical composition of the Earth's atmosphere and the reactions and interactions within it.
One of the major areas of study is how pollutants, such as CFCs, alter the chemical balance of atmospheric gases. The primary regions of academic focus include:

• The stratosphere, where the ozone layer is located.
• The troposphere, the atmospheric layer closest to the Earth, where weather occurs.

In the case of CFCs, atmospheric chemists look at how they travel from their source on Earth to the upper layers of the atmosphere. Once in the stratosphere, CFCs are broken down by UV radiation, releasing chlorine atoms. This is a straightforward example of how a relatively stable ground-level pollutant can have destructive effects high above. Atmospheric Chemistry helps us predict these outcomes and informs regulations that aim to reduce emissions and mitigate damage.