Since Poly Ethylene Glycol (PEG) is a water soluble
and non-toxic polymer it has found several industrial
applications and, hence, a number of researches have
worked on determination of thermodynamic properties of
aqueous solutions containing PEG [7-10].
Knowledge of activity coefficients of the constituent
components in aqueous solutions is essential in
calculation of phase equilibrium. A number of elaborate
researches have focused on measurement and modeling
of activity coefficients during recent years [11-13].
So far different direct and indirect methods for
measurement of activity coefficients of species in
aqueous solutions containing electrolytes are introduced.
Among which, isopiestic and potentiometric techniques
have been widely used [14-17]. Lin et al. [18] measured
activity of water in solutions containing PEG and