In Class 12 Organic Chemistry (Aldehydes & Ketones chapter), Tollens' Reagent is used as a chemical test to distinguish between Aldehydes and Ketones.
Composition: Ammoniacal silver nitrate — [Ag(NH₃)₂]⁺.
Positive Test: Silver mirror forms → Aldehyde present.
Negative Test: No silver mirror → Ketone present.
This test is called the Silver Mirror Test or Tollen's Test.
Tollens' reagent is a solution of ammoniacal silver nitrate — silver nitrate (AgNO₃) dissolved in aqueous ammonia (NH₃).
Formula: It contains the [Ag(NH₃)₂]⁺ ion (the diamminesilver(I) complex ion).
When Tollens' reagent is added to an aldehyde and gently warmed:
Reaction (simplified): RCHO + 2[Ag(NH₃)₂]⁺ + 2OH⁻ → RCOO⁻ + 2Ag↓ + 4NH₃ + H₂O
Ketones (like acetone) do NOT react with Tollens' reagent and produce no silver mirror. This is because ketones are not strong enough reducing agents.
Tollens' reagent is a solution of ammoniacal silver nitrate [Ag(NH₃)₂]⁺. It is used to distinguish aldehydes from ketones. Aldehydes reduce it to form a silver mirror (positive test), while ketones show no reaction.
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