Salt Effects on Volumetric Properties of Some n-Alkoxyethanols (C1Em, m = 1, 2, and 3) in Aqueous Solutions at 298.15 K

Abstract

Accurate density measurements over the whole composition range were made at a temperature of 298.15 K under ambient pressure for the mixtures of ethylene glycol monomethyl ether (2-methoxyethanol, C3H7O2; C1E1), or diethylene glycol monomethyl ether (2-(2-methoxyethoxy)ethanol, C5H12O3; C1E2), or triethylene glycol monomethyl ether [2-{2-(2-methoxyethoxy)ethoxy}ethanol, C7H16O4; C1E3) in aqueous salt solutions having a common anion with a view to examining the cationic effect on the volumetric properties. To gain insight into the mixing behavior, results of the density measurements were used to estimate excess molar volumes, V m E , apparent molar volumes, Vφ, i, partial molar volumes, $${\overline{V}}_{m,i}$$ , excess partial molar volumes, V m, E , and their limiting values at infinite dilution, V φ, ∞ , V m, ∞ , and V m, ,∞ , respectively. Aqueous solutions of the chlorides of lithium, sodium, potassium, and calcium in a concentration range to ca. 1 mol-kg−1 were chosen for investigation as this concentration is used most frequently in applied chemistry. All mixtures except that containing lithium chloride show a decrease in the magnitude of V m E with the addition of a salt when compared to salt-free mixtures. Comparison of the derived volumes at infinite dilution suggested modification of the water structure as well as an electrostatic interaction between the ionic species and an alkoxyethanol molecule.