Clausius Clapiron equation For the change of phase of a substance (e.g. solid to liquid, liquid to vapor etc.) the rate of change of saturation vapor pressure with temperature is given by,
¶ p/¶ T =L [T(V2 - V1)]-1
where T is the temperature at which change of phase takes place, V1 and V2, the specific volumes (volume per unit mass) in the first and second phase respectively, and L the latent heat.
The Clausius Clapiron equation can be used to calculate latent heat of evaporation of a liquid at various temperatures, if we know the value of V2 and the rate of change of saturation vapor pressure with temperature. Another application of eq.(c11) is the calculation of change of melting point of a solid with pressure.