Question

The electron cloud of HF is smaller than that of F2, however, HF has a much higher boiling point than F2 has. Which of the following explains how the dispersion-force model of intermolecular attraction does not account for the unusually high boiling point of HF?

A. F₂ is soluble in water, whereas HF is insoluble in water.
B. The F₂ molecule has a greater mass than the HF molecule has.
C. Liquid F₂ has weak dispersion force attractions between its molecules, whereas liquid HF has strong ionic interactions between H+ and F- ions.
D. Liquid F₂ has weak dispersion force attractions between its molecules, whereas liquid HF has both weak dispersion force attractions and hydrogen bonding interactions between its molecules.

Answer 1

The unusually high boiling point of HF compared to F2 cannot be explained by the dispersion-force model of intermolecular attraction. HF has additional intermolecular forces known as hydrogen bonding interactions between its molecules.

Step-by-step explanation:

The unusually high boiling point of HF compared to F2 cannot be explained by the dispersion-force model of intermolecular attraction. The dispersion forces depend on the size and mass of the molecules, with larger and heavier molecules having stronger dispersion forces. In the case of HF and F2, the dispersion forces would suggest that F2 should have a higher boiling point. However, HF has additional intermolecular forces known as hydrogen bonding interactions between its molecules. Hydrogen bonding is a particularly strong form of dipole-dipole interaction that occurs when hydrogen is bonded to electronegative atoms such as F, O, or N.