Ionic solvation of tetrabutylammonium hexafluorophosphate in pure nitromethane, 1,3-dioxolane and nitrobenzene: A comparative physicochemical study

Abstract

Electrolytic conductivities ( Λ), densities ( ρ), viscosities ( η), refractive indices ( n D) and speed of sound ( u) of tetrabutylammonium hexafluorophosphate (Bu 4NPF 6) have been studied in nitromethane (NM), 1,3-dioxolane (DO) and nitrobenzene (NB) at 298.15 K. The limiting molar conductivities ( Λ o), association constants ( K A), and the distance of closest approach of the ion ( R) have been evaluated using the Fuoss conductance equation (1978). The Walden product is obtained and discussed. The deviation of the conductmetric curves ( Λ vs √ c) from linearity for the salt in 1,3-dioxolane indicates triple-ion formation, and therefore the corresponding conductance data have been analyzed by using the Fuoss–Kraus theory of triple-ions. The limiting apparent molar volumes ( ϕ V), experimental slopes ( S V * ) derived from the Masson equation, and viscosity A and B coefficients using the Jones–Dole equation have been interpreted in terms of ion–ion and ion–solvent interactions, respectively. Molar refraction ( R M) have been calculated using the Lorentz–Lorenz equation. The adiabatic compressibility ( β S) has been evaluated using the u values. There after, the limiting apparent molar adiabatic compressibility ( ϕ K o ) have been calculated and discussed.