Question:
Which of the following compounds on reaction with ammonical silver nitrate solution forms precipitate of silver?
Which of the following compounds on reaction with ammonical silver nitrate solution forms precipitate of silver?
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Ammoniacal silver nitrate is just the formal chemical name for Tollens' reagent! Always remember: Aldehydes (compounds ending in "-al" like Ethanal) give a positive silver mirror result instantly!
Updated On: Jun 3, 2026
- Ethanal
- Ethanoic acid
- Ethanol
- Ethoxy ethane
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Verified By Collegedunia
The Correct Option is A
Solution and Explanation
Step 1: Understanding the Question:
The question asks to identify the compound that reduces ammoniacal silver nitrate solution (Tollens' reagent) to yield a solid shiny precipitate of elemental silver (the classic silver mirror test).
Step 2: Detailed Explanation:
Ammoniacal silver nitrate solution acts as Tollens' reagent, which is a mild oxidizing agent. This reagent reacts selectively with aldehydes. Aldehydes are easily oxidized into their corresponding carboxylate anions, and in turn, they reduce the silver complex ions ($\text{[Ag(NH}_3)_2]^+$) down to metallic silver metal atoms that coat the inner walls of the vessel: $$ \text{R-CHO} + 2[\text{Ag(NH}_3)_2]^+ + 3\text{OH}^- \longrightarrow \text{R-COO}^- + 2\text{Ag}_{(s)}\downarrow + 4\text{NH}_3 + 2\text{H}_2\text{O} $$ Among the given choices:
• Ethanal ($\text{CH}_3\text{CHO}$) is an aldehyde, so it gives a positive Tollens' test.
• Ethanoic acid (carboxylic acid), Ethanol (alcohol), and Ethoxy ethane (ether) are resistant to oxidation by Tollens' reagent and will not produce a silver precipitate.
Step 3: Final Answer: The compound that forms a silver precipitate upon reacting with ammoniacal silver nitrate is Ethanal, which corresponds to option (A).
The question asks to identify the compound that reduces ammoniacal silver nitrate solution (Tollens' reagent) to yield a solid shiny precipitate of elemental silver (the classic silver mirror test).
Step 2: Detailed Explanation:
Ammoniacal silver nitrate solution acts as Tollens' reagent, which is a mild oxidizing agent. This reagent reacts selectively with aldehydes. Aldehydes are easily oxidized into their corresponding carboxylate anions, and in turn, they reduce the silver complex ions ($\text{[Ag(NH}_3)_2]^+$) down to metallic silver metal atoms that coat the inner walls of the vessel: $$ \text{R-CHO} + 2[\text{Ag(NH}_3)_2]^+ + 3\text{OH}^- \longrightarrow \text{R-COO}^- + 2\text{Ag}_{(s)}\downarrow + 4\text{NH}_3 + 2\text{H}_2\text{O} $$ Among the given choices:
• Ethanal ($\text{CH}_3\text{CHO}$) is an aldehyde, so it gives a positive Tollens' test.
• Ethanoic acid (carboxylic acid), Ethanol (alcohol), and Ethoxy ethane (ether) are resistant to oxidation by Tollens' reagent and will not produce a silver precipitate.
Step 3: Final Answer: The compound that forms a silver precipitate upon reacting with ammoniacal silver nitrate is Ethanal, which corresponds to option (A).
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