Ionic interactions in aqueous electrolyte-polyelectrolyte mixtures: Comparisons with mixtures of sodium chloride with the model electrolyte sodiumpara-ethylbenzenesulfonate at 25°C

Osmotic coefficients for aqueous mixtures of sodium chloride with sodiumpara-ethylbenzenesulfonate NapEBS and lithiumpara-ethylbenzenesulfonate LipEBS with NapEBS obtained by the gravimetric isopiestic vapor pressure comparison method are interpreted with the Scatchard neutral-component and with the Pitzer ion-component equations. Ionic and mean ionic activity coefficients for Na⁺ and Cl^– ions and for NaCl, respectively, were also determined with an electrochemical cell. The ±(NaCl) values at constant unit ionic strength,I=1.00, were compared with those computed from osmotic-coefficient measurements. Strong anion-anion interactions were observed in the NaCl-NapEBS mixtures.