Activity coefficients of naclo₄ in (Peg 4000 + h₂o) mixtures at 288.15, 298.15 and 308.15 k

The cell potential of the cell containing two ion-selective electrodes (ISE), Na-ISE | NaClO₄ (m), PEG 4000 (Y), H2O (100-Y) | ClO₄-ISE has been measured at temperatures of (288.15, 298.15, and 308.15) K as a function of the weight percentage Y of PEG 4000 in a mixed solvent at a 1 Mpa and the standard state for measured activity coefficients will be a solution of the salt in pure water. Y was varied between (0 and 25) wt.% in five-unit steps and the molality of the electrolyte (m) was between 0.05 mol kg^-1 and almost saturation. The values of the standard cell potential were calculated 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 the standard electromotive force was determined, the mean ionic activity coefficients for NaClO₄, the Gibbs energy of transfer from the water to the PEG 4000-water mixture, and the primary NaCl hydration number were calculated.