Thermodynamic properties of the ternary system (KBr + PEG 4000 + water) by potentiometric method at T = (288.2, 298.2, and 308.2) K

Abstract

The goal of this research is to evaluate the mean ion activity coefficients (γ±) of the mixtures containing KBr + PEG 4000 + H2O (PEG stands for poly(ethylene glycol)) as well as some other thermodynamic quantities including solvent osmotic coefficients (φ), excess Gibbs energies (GE), standard Gibbs energies of transference (ΔGt0), and primary hydration number (nhydr). The experiment was employed by potentiometric measurement using the cell with two ion-selective electrodes (abbreviated as ISE) at (288.2, 298.2, and 308.2) K, and the mass fraction of PEG 4000 ranged from w = (0 to 0.20) with an increment of 0.05. The type of the cell is as follows:K–ISE | KBr (m), PEG 4000 (w), H2O (1-w) | Br–ISE.Nernst's equation was used to combine the Debye-Hückel and Pitzer models with potentiometric values. Pitzer ion interaction parameters (β0, β1, and Cφ) and Debye-Hückel model parameter (a) were evaluated. Moreover, the Bjerrum parameter (q) was calculated.