Boiling point

The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid.

A liquid may change to a gas at temperatures below the boiling point through the process of evaporation.
Any change of state from a liquid to a gas at boiling point is considered vaporization.

Boiling Point Definition

The boiling point is the temperature at which the vapor pressure of a liquid equals the external pressure surrounding the liquid. Therefore, the boiling point of a liquid depends on atmospheric pressure. The boiling point becomes lower as the external pressure is reduced.