The latent heat of vaporisation of a substance can be calculated from

The Clausius-Clapeyron equation relates the vapor pressure of a substance to the temperature and describes the phase transition line, given by:
$$\frac{d\ln P}{dT}=\frac{\Delta H_{\text{vap}}}{R{T}^2}$$

Hence, it allows for the determination of the latent heat of vaporisation ($\Delta H_{\text{vap}}$).