Explain why propanol has higher boiling point than that of the butane?

The difference in boiling points between propanol and butane primarily stems from differences in their molecular structures and intermolecular forces.

Propanol (specifically n-propanol, or 1-propanol) has a higher boiling point than butane due to several factors:

Molecular Size: Propanol is a larger molecule compared to butane. Propanol has a longer carbon chain, which results in greater surface area and more opportunities for intermolecular forces to act between molecules. These intermolecular forces, such as van der Waals forces and dipole-dipole interactions, require more energy to overcome, leading to a higher boiling point.

Hydrogen Bonding: Propanol contains an -OH (hydroxyl) functional group, which allows it to participate in hydrogen bonding. Hydrogen bonds are stronger than the van der Waals forces present in butane molecules. The presence of hydrogen bonding in propanol increases the attraction between molecules, requiring more energy to break the bonds and boil the liquid.

In contrast, butane is a smaller molecule with a simple linear structure and lacks functional groups that can participate in significant hydrogen bonding. Therefore, the intermolecular forces between butane molecules are weaker, requiring less energy to overcome and resulting in a lower boiling point compared to propanol.

In summary, propanol's higher boiling point compared to butane is mainly due to its larger size, greater molecular complexity, and the presence of hydrogen bonding, all of which contribute to stronger intermolecular forces.