Problem 32 - Chemistry in 30 days

Question

The secondary pollutants which is formed by dissolution is (a) \(\mathrm{SO}_{3}\) (b) NO (c) \(\mathrm{H}_{2} \mathrm{SO}_{4}\) (d) none of these

Step-by-Step Solution

Answer

(c) \(\mathrm{H}_2\mathrm{SO}_4\) is the secondary pollutant formed by dissolution.

Step 1: Understanding the Question

We need to identify a secondary pollutant that is formed by dissolution. A secondary pollutant is not emitted directly; it forms in the atmosphere through chemical reactions. Dissolution typically involves a substance dissolving in water, leading to a chemical reaction.

Step 2: Analyzing Options for Dissolution

Analyze each option to see if it can form through dissolution: (a) \(\mathrm{SO}_3\) is a primary molecule that can dissolve in water to form secondary pollutants, specifically sulfurous acid. (b) NO is a primary pollutant and doesn't become a secondary pollutant typically through dissolution.(c) \(\mathrm{H}_2\mathrm{SO}_4\) results from dissolution processes where \(\mathrm{SO}_3\) dissolves in water to form sulfuric acid, a secondary pollutant.(d) 'none of these' is not correct since \(\mathrm{H}_2\mathrm{SO}_4\) is indeed formed through dissolution.

Step 3: Selecting the Correct Option

After analyzing, the correct option is (c) \(\mathrm{H}_2\mathrm{SO}_4\), as it is a secondary pollutant formed through the dissolution of \(\mathrm{SO}_3\) in water.

Key Concepts

Dissolution in Chemistry

Dissolution in chemistry is a process where a solute (a substance) dissolves in a solvent (typically a liquid) to form a solution. This transformation allows molecules of the solute to become evenly distributed within the solvent.
In the context of atmospheric chemistry, dissolution plays a crucial role in the formation of secondary pollutants. For example, sulfur trioxide (\(\mathrm{SO}_{3}\)) can dissolve in atmospheric water droplets.

• This interaction forms sulfurous acid, and under certain conditions, further reacts to create sulfuric acid, a well-known secondary pollutant.
• Dissolution thus acts as a precursor step, enabling more complex chemical reactions to occur in the environment.

Understanding dissolution helps clarify the pathway from primary pollutants to secondary pollutants.

Formation of Sulfuric Acid

Sulfuric acid (\(\mathrm{H}_{2} \mathrm{SO}_{4}\)) is an example of a secondary pollutant that forms through a series of chemical reactions in the atmosphere. To comprehend its formation:

• First, primary pollutants like sulfur dioxide (\(\mathrm{SO}_{2}\)) are released into the atmosphere from various sources, including burning fossil fuels.
• Once in the atmosphere, \(\mathrm{SO}_{2}\) is oxidized to form sulfur trioxide (\(\mathrm{SO}_{3}\)).
• Then, \(\mathrm{SO}_{3}\) dissolves in water droplets present in the air, leading to the formation of sulfuric acid.

This process transforms gaseous pollutants into acidic precipitation, which can have adverse environmental impacts. It illustrates how minor changes in atmospheric chemistry can lead to significant environmental effects.

Chemical Reactions in the Atmosphere

The atmosphere is a dynamic chemical system where numerous reactions occur, leading to the production of secondary pollutants. These processes are important for understanding environmental chemistry:

• Reactions often start with primary pollutants, such as sulfur dioxide (\(\mathrm{SO}_{2}\)) or nitrogen oxides (\(\mathrm{NO}_{x}\)), which are emitted from industrial activities.
• Through photochemical and oxidative reactions, these primary pollutants transform into secondary pollutants like sulfuric acid (\(\mathrm{H}_{2} \mathrm{SO}_{4}\)).
• Moreover, atmospheric conditions such as sunlight, temperature, and humidity can affect these chemical transformations.

Understanding these reactions helps us grasp the complexity of pollution and climate change, emphasizing the need for monitoring and mitigating air pollution.