Concept Explanation: Reaction of Lead Sulphide with Dilute Nitric Acid

When lead sulphide (PbS) reacts with dilute nitric acid (HNO₃), it undergoes a redox reaction where PbS is oxidized. Dilute nitric acid acts as an oxidizing agent. The balanced chemical equation for this reaction is:

$3\mathrm{PbS}+8\mathrm{HNO}3(\mathrm{dilute})\to 3\mathrm{Pb}(\mathrm{NO}3)2+2\mathrm{NO}+3S+4H2O$

From this equation, we can identify the products formed:

• Lead nitrate [Pb(NO₃)₂]
• Nitric oxide (NO)
• Sulphur (S)
• Water (H₂O)

Now, comparing with the given options:

Step 1: Check each option against the products in the balanced equation.

Step 2: Lead nitrate is formed.

Step 3: Nitric oxide is formed.

Step 4: Sulphur is formed.

Step 5: Nitrous oxide (N₂O) is not formed in this reaction. It is not listed in the products.

Final Answer: Nitrous oxide is not formed.

Related Topics

• Redox Reactions
• Properties of Nitric Acid
• Reactivity of Sulphides with Acids
• Oxidizing Nature of Nitric Acid

Important Formulae and Theory

Balanced Equation:

$3\mathrm{PbS}+8\mathrm{HNO}3\to 3\mathrm{Pb}(\mathrm{NO}3)2+2\mathrm{NO}+3S+4H2O$

Key Points:

• Dilute nitric acid oxidizes PbS to S (sulphur) and itself gets reduced to NO.
• Concentrated nitric acid would oxidize PbS to PbSO₄ (lead sulphate) instead of sulphur.
• Nitrous oxide (N₂O) is typically produced in reactions involving dilute nitric acid and certain other metals or compounds, but not in this case.