Correlation of Thermophysical Properties of Ionic Liquids with Empirical Equations

Density, refractive index, surface tension, dynamic and kinematic viscosities of some ionic liquids are investigated. The thermal expansion coefficient, molecular volume, standard entropy, lattice energy, surface entropy and surface energy for the ionic liquids are estimated from the experimental values of the density and surface tension. The Vogel-FulcherTammann (VFT), modified VFT, Arrhenius and Litovitz equations are applied to correlate experimental values of dynamic and kinematic viscosities as a function of temperature. The relation between densities and refractive indexes are correlated satisfactorily with several empirical equations such as Lorentz-Lorenz, Dale-Gladstone, Eykman, Oster, Arago-Biot, Newton and Modified-Eykman. Finally, the relation between surface tensions and viscosities are investigated and the parachor method is used to predict densities, refractive indexes and surface tensions of the ionic liquids.

Keywords:

Ionic liquid , correlation , temperature dependence , physical properties , empirical equations