Question

give a chemical test to distinguish between Ethanal and propanal.

Answer 1

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.

Answer 2

Answer: Iodofrom is the chemical test to distinguish between Ethanal and propanal.

Explanation:

The chemical test which distinguishes ethanal from propanal is iodoform test.

Iodoform test is used to detect the presence of carbonyl compounds having structure $RCOCH_{3}$ and alcohols having structure $RCH(OH)CH_{3}$.

To carry out positive iodoform test, it is necessary to have a methy ketone or methyl alcohol.

The formula for ethanal is $CH_{3}CHO$. As ethanal has a methyl group attached to the CHO, therefore it will give a positive iodoform test.

Whereas the formula for propanal is $CH_{3}CH_{2}CHO$. As there is no $CH_{3}$ attached to the CHO so, it will not give iodoform test.

Thus, iodofrom is the chemical test to distinguish between Ethanal and propanal.