Aim\ To study method for calculating free energy of mixing of polymer system. Methods\ A new method for treating experimental data on concentration dependence of chemical potential is advanced. Various presented methods for calculating free energy of mixing through the Flory-Huggins equation are compared. Results\ Relations on concentration dependence of chemical potential are gained by various methods. Conclusion\ As compared with other known calculating procedures

the new method is shown to provide more precise estimates of free energy of mixing.