Accurate evaluation of the internal energy, free energy, entropy and enthalpy of non-polar molecules by using virial coefficients

In this work, we suggest an alternative method for evaluating the internal energy, free energy, entropy and enthalpy using the second virial coefficient over the Lennard-Jones (12-6) potential. The proposed formulae guarantees an accurate and fast calculation of the internal energy, free energy, entropy and enthalpy. By using the obtained analytical expressions, we have calculated the internal energy, free energy, entropy and enthalpy of the molecules (Cl2, N2O, CH4, C2H2, AsH3, C6H6, Br2, COS, C2N2, Air, CH2, HCl, I2, SO2, He, Ne, Kr, Xe, H2, O2, N2, A, and CO2) over the temperature range from 500°K to 5000 °K and the pressure range from 1 atm to approximately 300 atm. The results obtained by the present analytical expressions are in good agreement with the literature data.