Question

Wrie chemical test to distinguish between aldehyde and ketone (Give reason).

Answer 1

• Tollens’ test, also known as silver-mirror test, is a qualitative laboratory test used to distinguish between an aldehyde and a ketone. It exploits the fact that aldehydes are readily oxidized, whereas ketones are not. Tollens’ test uses a reagent known as Tollens’ reagent, which is a colorless, basic, aqueous solution containing silver ions coordinated to ammonia $\left[Ag\right(N{H}_3){]}^{2+}$.
  
• Tollens’ reagent oxidizes an aldehyde into the corresponding carboxylic acid.The reaction is accompanied by the reduction of silver ions in Tollens’ reagent into metallic silver, which, if the test is carried out in a clean glass test tube, forms a mirror on the test tube.
  
• Thus Aldehydes forms a silver mirror on test tube when treated with Tollens' reagent whereas Ketones doesn't show it.