Watson Equation: For Hvap for the liquid-gas phase boundary

ln(Hvap/Hvapo) = a1 + åai ×Tri-2×ln(1-Tr) , where the summation is from i = 2 to nTerms

Tr = T/Tc, Tc is the critical temperature, and Hvapo = 1 kJ/mol

Evaluation Results:

The example is for fitted enthalpies of vaporization for benzene.