BRAINCAKETollens' Reagent
Tollens' reagent is a mild oxidising agent used to distinguish aldehydes from ketones. It is made from silver nitrate solution and aqueous ammonia, and contains the complex ion [Ag(NH3)2]+. It should be freshly prepared.
The test: add Tollens' reagent to the sample in a clean test tube and warm it in a hot water bath. A water bath is used rather than a flame because organic compounds are flammable.
• Aldehyde: a silver mirror forms on the inside of the tube (or a black-grey precipitate of silver).
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More in Aldehydes and Ketones
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All 9 lessons in Aldehydes and Ketones · All AQA A-level Chemistry topics