In this work, the ternary and quaternary electrolyte systems
including NaCl þ C2H5OH þ H2O and NaCl þ KCl þ C2H5OH þ H2O
are investigated. The activity coefficient measuring is performed in
mixed solvent with different alcohol mass fractions x (x ¼ 0.10,
0.20, 0.30, 0.40, and 0.50) in water. The mean activity coefficients
modeling for The Pitzer (P) and the modified Pitzer (MP) equations
are both used in this work for NaCl þ C2H5OH þ H2O and
NaCl þ KCl þ C2H5OH þ H2O at 298.15 K. The MP equation and
Pitzer graphical method are generally well presented by the model.