Question

(b) Give a simple chemical test to distinguish between propanal and propanone.

Hint:

The Tollens' test is a traditional method to identify aldehydes. Aldehydes reduce silver ions to form a silver mirror, whereas ketones do not react.

Answer 1

A simple chemical test to differentiate between propanal (an aldehyde) and propanone (a ketone) is the Tollens' test.
Propanal (Aldehyde): When treated with Tollens' reagent (ammoniacal silver nitrate), aldehydes reduce silver ions to metallic silver, creating a silver mirror on the inner surface of the test tube.
Propanone (Ketone): Ketones do not react with Tollens' reagent and, therefore, do not form a silver mirror.
Thus, the Tollens' test effectively distinguishes between an aldehyde and a ketone. \bigskip