Question

Why does water have a much higher boiling point than methane even though the water (H2O) and methane (CH4) molecules are approximately the same size?

a) Water molecules have stronger intermolecular forces.
b) Methane molecules have stronger intermolecular forces.
c) Water molecules have a lower molecular weight.
d) Methane molecules have a higher molecular weight.

Answer 1

Water molecules have stronger intermolecular forces than methane molecules, which results in a higher boiling point for water.

Step-by-step explanation:

Molecules with hydrogen atoms bonded to electronegative atoms such as O, N, and F tend to exhibit unusually strong intermolecular interactions due to hydrogen bonds. These result in much higher boiling points than are observed for substances in which dipole-dipole forces or London dispersion forces dominate.

Water molecules, which have hydrogen bonds, have stronger intermolecular forces compared to methane molecules, which only have London dispersion forces. Therefore, option a) Water molecules have stronger intermolecular forces is the correct answer.