Activity coefficients of LiCl in (PEG 4000 + water) at T = (288.15, 298.15, and 308.15) K

Abstract

The electromotive force of the cell containing two ion-selective electrodes (ISE), Na-ISE | LiCl ( m ) , PEG 4000 ( w ) , H 2 O ( 1 - w ) | Cl-ISE has been measured at temperatures of (288.15, 298.15, and 308.15) K as a function of the mass fraction of PEG 4000 ( w) in the mixture. w was varied between 0 and 0.25 in 0.05-unit steps and the molality of the electrolyte ( m) was between c.a. (0.03 and 5.8) mol · kg −1. The values of the standard electromotive force, E ∘ , were determined using routine methods of extrapolation, together with extended Debye–Hückel and Pitzer equations. The results obtained produced good internal consistency for all the temperatures studied. Once E ∘ was determined, the mean ionic activity coefficients for LiCl, the Gibbs free energy of transfer from the water to (PEG 4000 + water), and the primary LiCl hydration number were calculated.