Q. n-butylamine (I), diethylamine (II) and N, N-dimethylethylamine (III) have the same molar mass. The increasing order of their boiling point is
A) III < II < I
B) I < II < III
C) II < III < I
D) II < I < III
Explanation
(a)
Intermolecular H-bonding is more in primary amines than in secondary amines as there are two H-atom available for H-bonding. Tertiary amines do not have intermolecular H-bonding due to absence of H-atom available for H-bonding. Therefore, the order of boiling points of the given amines is as fallows
$nC_{4}H_{9}NH_{2}$ > $\left( C_{2}H_{5} \right)_{2}NH$ > $C_{2}H_{5}N\left( CH_{3} \right)_{2}$
b.p. 350.8 K b.p. 329.3 K b.p. 310.5 K
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.