Question
Arrange the following compounds in the increasing order of their boiling points:
CH3CH2CH2CHO, CH3CH2CH2CH2OH, H5C2—O—C2H5, CH3CH2CH2CH2CH3.
Solution
The molecular masses of these compounds are in the range of 72 to 74. Since only n-butanol molecules are associated due to extensive inter-molecular hydrogen bonding, therefore, the boiling points of n-butanol would be the highest. Butanal is more polar than ethoxy ethane. Therefore, the intermolecular dipole-dipole attraction is stronger in the former. The p-pentane molecules have only weak Van der Waals forces. In view of the above facts the following compounds are arranged as per their increasing order of boiling points.
CH3CH2CH2CH2CH3<H5C2—O-C2H5 < CH3CH2CH2CHO < CH3CH2CH2CH2OH
