Ionic mobility and ionic association of singly charged ions in glycerol

Abstract

Experimental molar conductivity data for KCl, NaCl and LiCl in glycerol at 298.15 K were analysed by least-square fitting in the concentration range 0.5–100 mol m⁻³in order to compute the values of the molar conductivity at infinite dilution Λ⁰and the Onsager constant S. Using previously measured transference numbers and assuming the Kohlrausch infinite dilution law, the limiting ionic mobilities were deduced. The results obtained show that the transport mechanisms in this solvent and other similar hydrogen-bonded solvents such as water and ethylene glycol are the same. The data were also interpreted in terms of ion–ion and ion–solvent interactions using the Fuoss paired ion model in the concentration range 0.5–100 mol m⁻³. The fitting of Fuoss’ equation of 1978 to these data led us to an estimate of the ionic association by computing the conductimetric pairing constants. The latter were further analysed by Gilkerson's equation to yield the difference between the solvation energy of the free ions and the ion pairs. The computed values allow an estimation of whether the electrolyte is a structure maker or a structure breaker.