The equilibrium vapor pressure of a liquid is the most common way of examining the change of the liquid/vapor equilibrium. When the vapor pressure above a liquid reaches equilibrium it is said to be saturated.

The relationship between vapor pressure and temperature is described by the Clausius-Clapeyron Equation. [Local].

The Clausius-Clapeyron equation fails near the critical temperature. A better equation for the purpose of calculating vapor pressure is termed the Antoine equation. [Local]

The connection between boiling, vapor pressure, and temperature [Local] is important. Students often are confused by these concepts.