Tollens' reagent
What Tollens' reagent means in Chemistry A-Level, as defined for AQA, OCR.
Definitions of Tollens' reagent
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Reference: OCR
Colourless ammoniacal silver nitrate, [Ag(NH₃)₂]⁺, which an aldehyde reduces to a silver mirror of metallic silver when warmed gently, whereas a ketone gives no change.
Ammoniacal silver nitrate, [Ag(NH₃)₂]⁺, made by adding aqueous ammonia to silver nitrate until the precipitate just dissolves.
Made fresh by adding aqueous ammonia to silver nitrate solution until the precipitate redissolves, giving the ion [Ag(NH₃)₂]⁺.
Ammoniacal silver nitrate is reduced by an aldehyde on warming to give a silver mirror, but not by a ketone.
Topics that use Tollens' reagent
- Aldehydes and ketones (A-level only) (AQA A-Level)
- Carbonyl compounds (OCR A-Level)
- Chromatography and qualitative analysis (OCR A-Level)
Related terms
- Oxidation of aldehydes
- contrast with ketones
- Distinguishing aldehydes from ketones
- Fehling's solution
- Reduction of silver(I) to silver metal
- reduction with NaBH₄
- 2,4-dinitrophenylhydrazine test
- 2,4-dinitrophenylhydrazone
Using Tollens' reagent in the exam
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