In the material, evaporation/vaporization refers to which phase change?

• A. Gas to liquid
• B. Solid to gas
• C. Liquid to gas (endothermic)
• D. Deposition

Answer: (C)

Evaporation/vaporization is the liquid-to-gas change. When heat is added, molecules at the surface gain enough energy to overcome the liquid’s intermolecular forces and escape into the air as a gas, so this process is endothermic (energy-absorbing). Evaporation can occur at any temperature on the surface, while boiling is a related form that happens throughout the liquid at a specific temperature when the vapor pressure matches the surrounding pressure. Other phase changes include condensation (gas to liquid), sublimation (solid to gas), and deposition (gas to solid), which are not what evaporation refers to.