List the four types of intermolecular forces discussed in this chapter in order of increasing relative strength.

What are dispersion forces? How does the strength of dispersion forces relate to molar mass?

Is the boiling of water endothermic or exothermic? What is the sign of $\Delta H$ for the boiling of water? For the condensation of steam?

Is the melting of ice endothermic or exothermic? What is the sign of $\Delta H$ for the melting of ice? For the freezing of water?

Explain how ice cubes cool down beverages.

Why are water droplets spherical?

Explain why the water in a cup placed in a small ice chest (without a refrigeration mechanism) initially at $-5^{\circ} \mathrm{C}$ does not freeze.

Explain what happens when a liquid boils.

Explain why a steam burn from gaseous water at $100^{\circ} \mathrm{C}$ is worse than a water burn involving the same amount of liquid water at $100^{\circ} \mathrm{C}$.

Explain how sweat cools the body.

What is the vapor pressure of a substance? How does it depend on temperature and strength of intermolecular forces?

Explain condensation and dynamic equilibrium.

Acetone evaporates more quickly than water at room temperature. What can you say about the relative strength of the intermolecular forces in the two compounds? Which substance is more volatile?

What is the boiling point of a liquid? What is the normal boiling point?