To establish the ascending order of boiling points for n-Butane, Ethoxyethane (Diethyl ether), Pentanal, and Pentan-1-ol, an analysis of their intermolecular forces—Van der Waals forces, dipole-dipole interactions, and hydrogen bonding—is necessary.
- n-Butane: Being an alkane, it exhibits only weak Van der Waals forces, lacking substantial dipole moments or hydrogen bonding capacity, thus possessing a low boiling point.
- Ethoxyethane (Diethyl ether): It displays stronger Van der Waals forces than n-butane and engages in dipole-dipole interactions due to its ether functional group, resulting in a higher boiling point than n-butane.
- Pentanal: As an aldehyde, its polar carbonyl group facilitates stronger dipole-dipole interactions than ethoxyethane, leading to a higher boiling point compared to ethoxyethane.
- Pentan-1-ol: The presence of a hydroxyl group (-OH) enables hydrogen bonding, a force that significantly elevates its boiling point above that of the other compounds.
Consequently, the sequence of increasing boiling points is: n-Butane, Ethoxyethane, Pentanal, Pentan-1-ol.