Higher intermolecular forces = ________ B.P.

Higher intermolecular forces = ________ B.P.

• A. Higher
• B. Lower
• C. No change
• D. It depends on temperature

Answer: (A)

Stronger intermolecular forces make it harder for molecules to escape into the gas phase, so more heat is needed to reach the point where vapor pressure equals the external pressure. The boiling point is that temperature, so stronger forces raise it. That’s why the correct completion is “Higher.” If forces were weaker, the boiling point would be lower; saying no change or that it depends on temperature would miss the direct relationship between the strength of attractions and the energy required to vaporize.

Stronger intermolecular forces make it harder for molecules to escape into the gas phase, so more heat is needed to reach the point where vapor pressure equals the external pressure. The boiling point is that temperature, so stronger forces raise it. That’s why the correct completion is “Higher.” If forces were weaker, the boiling point would be lower; saying no change or that it depends on temperature would miss the direct relationship between the strength of attractions and the energy required to vaporize.