Question

Which simple chemical test is used to distinguish between ethanal & propanal?

• A. Iodoform test
• B. Tollen's test
• C. Fehling's test
• D. Lucas test

Answer 1

Answer: (B)

Tollen's test

Answer 2

The simple chemical test used to distinguish between ethanal (acetaldehyde) and propanal (propionaldehyde) is the Tollen's test.

Tollen's test is based on the oxidation of an aldehyde to a carboxylic acid in the presence of Tollens' reagent, which is an alkaline solution of silver nitrate $(AgNO_3).$ Ethanal, being a primary aldehyde, readily undergoes oxidation in the Tollen's test and produces a silver mirror on the inner surface of the reaction vessel. Propanal, being a secondary aldehyde, does not react with Tollens' reagent and does not produce a silver mirror.

Therefore, the correct option is (B): the Tollen's test is used to distinguish between ethanal and propanal.