Britannica Sources used in this answer

How does boiling differ from evaporation?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Diagram showing four physical states of matter: solid with tightly packed molecules, liquid with loosely packed molecules, gas with widely spaced molecules, and plasma with free electrons and nuclei, each labeled with descriptions and an arrow indicating increasing energy. — phase States of matter.

Both boiling and evaporation are forms of vaporization, the process by which a substance transitions from a liquid to a gaseous phase. However, they differ significantly in how and where this transition occurs:

Boiling: This process occurs when the vapor pressure of a liquid equals the pressure exerted by the surrounding environment. Under these conditions, heat addition causes the formation of vapour bubbles within the liquid, which then rise to the surface. This typically happens at a specific boiling point determined by the applied pressure.123
Evaporation: Unlike boiling, evaporation occurs at temperatures below the boiling point. It is a surface phenomenon where individual molecules with sufficient kinetic energy escape from the surface of the liquid into the surrounding atmosphere.4

While boiling is characterized by the internal formation of bubbles throughout the liquid, evaporation is a more gradual process occurring only at the liquid's surface.24