Question

Ozone in stratosphere is depleted by: (a) \(\mathrm{C}_{7} \mathrm{~F}_{16}\) (b) \(\mathrm{C}_{6} \mathrm{~F}_{6}\) (c) \(\mathrm{CF}_{2} \mathrm{Cl}_{2}\) (d) \(\mathrm{C}_{6} \mathrm{H}_{6} \mathrm{Cl}_{6}\)

Short answer

Option (c) \(\mathrm{CF}_{2} \mathrm{Cl}_{2}\) is the compound that depletes ozone.

Step-by-step solution

Understand the Question

The exercise asks for the chemical compound that is responsible for the depletion of ozone in the stratosphere. We need to identify which of the given compounds is known for this effect.

Recall Ozone-Depleting Chemicals

CFCs (Chlorofluorocarbons) are known to deplete the ozone layer. They are compounds containing carbon, fluorine, and chlorine. The search is to identify if any given options fall under CFCs.

Analyze Each Option

- (a) \(\mathrm{C}_{7} \mathrm{~F}_{16}\) is a fluorocarbon and does not contain chlorine.- (b) \(\mathrm{C}_{6} \mathrm{~F}_{6}\) is also a fluorocarbon and does not contain chlorine.- (c) \(\mathrm{CF}_{2} \mathrm{Cl}_{2}\) is a chlorofluorocarbon, containing both chlorine and fluorine.- (d) \(\mathrm{C}_{6} \mathrm{H}_{6} \mathrm{Cl}_{6}\) is not a CFC; it's an organochlorine compound but doesn't fit the characteristic for ozone depletion.

Choose the Correct Option

Given the analysis, option (c) \(\mathrm{CF}_{2} \mathrm{Cl}_{2}\) is identified as a chlorofluorocarbon (CFC), which are known to deplete the ozone layer.

Key concepts

Chlorofluorocarbons (CFCs)

Chlorofluorocarbons, or CFCs, are a group of synthetic compounds that contain carbon, chlorine, and fluorine. They were originally developed in the early 20th century for use in refrigeration, air conditioning, and as propellants in aerosol sprays. CFCs are non-toxic, non-flammable, and chemically stable, which made them ideal for many industrial applications.

However, CFCs have a detrimental effect on the environment, especially on the ozone layer in the stratosphere. When CFCs are released into the atmosphere, they eventually rise to the stratosphere, where they are broken down by ultraviolet (UV) radiation. This breakdown releases chlorine atoms, which then participate in chemical reactions that destroy ozone molecules.

• Each chlorine atom from CFCs can destroy thousands of ozone molecules, contributing significantly to ozone layer depletion.
• Due to their potency, even a small concentration of CFCs can cause substantial harm.

Efforts to reduce and eventually ban CFCs have been implemented globally through agreements like the Montreal Protocol, showcasing the importance of mitigating the harmful environmental impact of these compounds.

Stratosphere

The stratosphere is the second major layer of Earth's atmosphere, sitting above the troposphere and below the mesosphere. It extends approximately 10 to 50 kilometers above Earth's surface. The stratosphere is characterized by a relatively stable temperature profile, with temperatures increasing with altitude due to the absorption of UV radiation by ozone.

Ozone plays a critical role in the stratosphere by absorbing and scattering UV radiation from the sun. This not only warms the stratosphere but also provides a protective shield, preventing harmful UV radiation from reaching the Earth's surface.

• Without the protective layer of ozone, more UV radiation would reach the surface, increasing the risk of skin cancer in humans and harm to organisms.
• The health and stability of the ozone layer are crucial for maintaining the ecological balance.

The depletion of ozone in the stratosphere, primarily due to CFCs and other ozone-depleting substances, has led to the formation of what is commonly known as "ozone holes." Protecting the ozone layer is essential for safeguarding life on Earth.

Environmental Chemistry

Environmental chemistry is the scientific study of the chemical and biochemical phenomena that occur in natural places. It involves understanding the complex interactions between chemicals in the environment and human-made substances that impact these processes.

In terms of ozone layer depletion, environmental chemistry is crucial for understanding how chemical compounds, such as CFCs, interact with atmospheric constituents. Scientists use this knowledge to determine how substances affect the ozone layer, air quality, and climate change.

• Environmental chemistry helps in assessing the risk of chemical substances, allowing for informed policy and regulation creation.
• By understanding chemical reactions in the atmosphere, scientists can develop strategies to reduce pollution and environmental harm.

Combining insights from environmental chemistry with global cooperation has led to significant progress in addressing ozone layer depletion. Emphasizing the importance of environmental chemistry can lead to more sustainable practices and better protection of the Earth's atmosphere.