Molar enthalpy of vaporization (The Clausius-Clapeyron equation)
the molar enthalpy of vaporization
temperautre at one point
corresponding vapor pressure at temperature T1
temperature at another point
corresponding vapor pressure at temperature T2
The Clausius-Clapeyron equation for the liquid-vapor boundary may be used in either of two equivalent forms. If the corresponding temperature and pressure is known at two points, the enthalpy of vaporization can be determined.