Question

Give simple chemical tests to distinguish between the following pairs of compounds.
(i) Ethanal and Propanal
(ii) Benzoic acid and Phenol

Answer 1

i. Ethanal and propanal can be distinguished by iodoform test.
Iodoform test: Aldehydes and ketones having at least one methyl group linked to the carbonyl carbon atom responds to the iodoform test. Ethanal having one methyl group linked to the carbonyl carbon atom responds to this test. But propanal does not have a methyl group linked to the carbonyl carbon atom and thus, it does not respond to this state.

ii. Ferric chloride test: Phenol reacts with neutral $FeC{l}_3$ to form an iron-phenol complex giving violet colouration. But benzoic acid reacts with neutral $FeC{l}_3$ to give a buff coloured ppt. of ferric benzoate.