2026 Comprehensive Departmental Practice Test

Vaporization is the change from a liquid to a gas. When a liquid is heated, its molecules gain energy. Once they have enough energy to overcome the intermolecular forces holding them in the liquid, they escape into the air as a gas. This can happen in two ways: evaporation, which occurs at the surface at temperatures below the boiling point, and boiling, which happens throughout the liquid when it reaches its boiling point and vapor pressure matches the surrounding pressure.

Condensation is the reverse process (gas to liquid). Sublimation is solid turning directly into gas. Freezing is liquid turning into solid.