On the estimation of equivalent conductivity of electrolyte solutions; The effect of relative static permittivity and viscosity

The effect of a concentration-dependent relative static permittivity (RSP) and viscosity on the predictions of the equivalent conductivity models is studied. The full version and simplified version of the mean spherical approximation models along with four Debye-Hückel-Onsager (DHO) based equivalent conductivity models are used to predict the equivalent conductivity of nine 1:1 aqueous electrolyte solutions at 25°C. Three of the DHO based models have been developed in this study by combining the electrophoretic and relaxation effects that have been previously presented in the literature. To investigate the effect of RSP on the equivalent conductivity predictions, we have used three empirical RSP models along with the solvent's RSP. It has been shown that using a concentration-dependent RSP reduces the deviation of equivalent conductivity predictions from the experimental data. We have also investigated the effect of a concentration-dependent viscosity on the equivalent conductivity predictions. Our observations show that using a concentration-dependent viscosity sometimes improves and sometimes worsens the predictions.