ABSTRACT: Potentiometric investigation on {H2O+NaNO3+PEG1500} mixtures were made
at T=308.15K, using electrochemical cells with two ion-selective electrodes, (Na+
glass)
as the cation ion-selective electrode against (NO3
- solvent-polymer PVC) as the anion ion-selective
electrode. The mean ionic activity coefficients of NaNO3 were measured at different concentrations
of NaNO3 and PEG. Maximum concentration of electrolyte and PEG were 1 mol/kg and 0.12 mol/kg,
respectively. The experimental data was modeled by utilizing the modified Pitzer equation
and the activity coefficient ratio of PEG was evaluated by using Maxwell’s cross differential relation.