Question

Arrange the following in the increasing order of boiling point:

(i)$C_2{H}_{5}OH$

(ii)$(C{H}_3{)}_{2}NH$

(iii)$C_2{H}_{5}N{H}_2$

• A. i < ii < iii
• B. ii < i < iii
• C. iii < i < ii
• D. iii < ii < i

Answer 1

The correct option is D iii < ii < i

All the given compounds have intermolecular hydrogen bonding due to which their boiling points are higher. $C_2{H}_{5}OH$ possesses strongest hydrogen bonding because the $O$ is more electron negative than $N$ in other compounds. Therefore it has the highest boiling point. In $(C{H}_3{)}_{2}NH$ and $C_2{H}_{5}N{H}_2$, the latter has longer alkyl chain which makes hydrogen bonding weaker. Hence the order of boiling points is $iii<ii<i$