Problem 162 - A Complete Resource Book in Chemistry for JEE Main

Question

\(\mathrm{SO}_{2}\) will be obtained in: (a) \(\mathrm{PbS}+\) air (b) \(\mathrm{FeS}_{2}+\) air (c) \(\mathrm{ZnS}+\mathrm{air}\) (d) \(\mathrm{H}_{2} \mathrm{~S}^{2}+\mathrm{O}_{3}\)

Step-by-Step Solution

Answer

\(\mathrm{SO}_{2}\) is obtained in (a), (b), and (c).

Step 1: Identify the Reaction Components

For each option, identify the chemical components involved in the reaction. We have:- (a) Lead sulfide (\(\mathrm{PbS}\)) and air (usually providing \(\mathrm{O}_2\)).- (b) Iron disulfide (\(\mathrm{FeS}_2\)) and air.- (c) Zinc sulfide (\(\mathrm{ZnS}\)) and air.- (d) Hydrogen sulfide (\(\mathrm{H}_2\mathrm{S}\)) and a potential oxidizing agent, indicated as \(\mathrm{O}_3\).

Step 2: Determine the Reaction Equations

Write the potential chemical reaction for each case to see if \(\mathrm{SO}_{2}\) is formed:- (a) \(\mathrm{PbS} + \mathrm{O}_2 \rightarrow \mathrm{PbO} + \mathrm{SO}_2\)- (b) \(\mathrm{FeS}_2 + \mathrm{O}_2 \rightarrow \mathrm{Fe}_2\mathrm{O}_3 + \mathrm{SO}_2\)- (c) \(\mathrm{2ZnS} + \mathrm{3O}_2 \rightarrow \mathrm{2ZnO} + \mathrm{2SO}_2\)- (d) Examine \(\mathrm{H}_2\mathrm{S} + \mathrm{O}_3\), but note that \(\mathrm{O}_3\) typically reacts differently and might not produce \(\mathrm{SO}_2\).

Step 3: Analyze the Reaction Outcomes

For each reaction, consider if \(\mathrm{SO}_{2}\) is actually produced from the reaction equations established:- (a) \(\mathrm{SO}_{2}\) is produced.- (b) \(\mathrm{SO}_{2}\) is produced.- (c) \(\mathrm{SO}_{2}\) is produced.- (d) \(\mathrm{H}_2\mathrm{S}\) with \(\mathrm{O}_3\) may not directly produce \(\mathrm{SO}_2\); typically produces other sulfur-oxygen compounds.

Step 4: Conclusion on Which Reactions Produce \(\mathrm{SO}_2\)

From the analysis, \(\mathrm{SO}_2\) is obtained when the following options undergo reactions with air:- (a), (b), and (c) all produce \(\mathrm{SO}_2\).- Option (d) does not clearly end with \(\mathrm{SO}_2\) as a typical result.

Key Concepts

Chemical Reactions

Chemical reactions are the processes in which substances, known as reactants, are transformed into new substances, referred to as products. These reactions involve the breaking and forming of bonds between atoms. In the context of sulfur dioxide formation, we explore how different sulfur compounds, when combined with air (providing oxygen), undergo chemical transformations to produce sulfur dioxide (\( \mathrm{SO}_{2} \)).
One simple way to understand this is through the reaction equations. These equations illustrate how the reactants (sulfur compounds and oxygen) interact and rearrange to form the products (\( \mathrm{SO}_{2} \) and other compounds).

• Reactants are substances that start a chemical reaction.
• Products are substances that result from a chemical reaction.
• Chemical reactions often involve energy changes due to bond breaking/formation.
• The conservation of mass is a key principle; atoms are neither created nor destroyed.

Understanding these basic principles helps in predicting the feasibility of the reaction and the likely products.

Sulfur Compounds

Sulfur compounds are chemical compounds containing sulfur as an essential element. Sulfur is a non-metal with diverse chemical behavior, often forming compounds in combination with oxygen or metals. This exploration focuses on its role in forming sulfur dioxide (\( \mathrm{SO}_{2} \)) in chemical reactions.
Common sulfur compounds include lead sulfide (\( \mathrm{PbS} \)), iron disulfide (\( \mathrm{FeS}_2 \)), zinc sulfide (\( \mathrm{ZnS} \)), and hydrogen sulfide (\( \mathrm{H}_2\mathrm{S} \)). Each of these reacts differently when exposed to air or other oxidizing agents.

• Lead sulfide (\( \mathrm{PbS} \)): Reacts with oxygen to produce lead oxide and sulfur dioxide.
• Iron disulfide (\( \mathrm{FeS}_2 \)): Yields iron(III) oxide and sulfur dioxide upon reaction with oxygen.
• Zinc sulfide (\( \mathrm{ZnS} \)): Produces zinc oxide and sulfur dioxide when burnt in air.
• Hydrogen sulfide (\( \mathrm{H}_2\mathrm{S} \)): Its reaction with ozone is less straightforward, producing various sulfur-oxygen compounds.

Recognizing the characteristics and reactivity of these sulfur compounds assists in identifying their behavior and potential to yield \( \mathrm{SO}_{2} \).

Oxidation Reactions

Oxidation reactions involve the transfer of electrons between reactants, typically involving the addition of oxygen to a substance. These reactions are a crucial component in the formation of sulfur dioxide (\( \mathrm{SO}_{2} \)) from sulfur compounds.
In our exploration, these sulfur-containing compounds are oxidized in the presence of air, supplying oxygen. This oxygen acts as the oxidizing agent, facilitating the chemical transformation of the sulfur compounds into sulfur dioxide.

• Oxidation involves the increase in oxidation state of an element.
• The oxidizing agent (such as \( \mathrm{O}_2 \)) gains electrons, oxidizing the sulfur compound.
• These reactions often release energy, making them exothermic.

For reactions like those of \( \mathrm{PbS}, \mathrm{FeS}_2, \) and \( \mathrm{ZnS} \), the sulfur compounds undergo oxidation to produce metal oxides and \( \mathrm{SO}_{2} \). In contrast, \( \mathrm{H}_2\mathrm{S} \) reacts with ozone (\( \mathrm{O}_3 \)) in a more complex oxidation process, rarely resulting in \( \mathrm{SO}_{2} \). Understanding these mechanisms is key to predicting and harnessing chemical reactions for industrial and environmental applications.