Assessment of Stokes-Einstein Equation in Combination of the Hole Theory for Estimating the Transport Properties of Ionic Liquid

In this paper, the validity of Stokes-Einstein (SE) equation for estimating the transport properties (e.g. viscosity) of imidazolium-based ionic liquids [Cnmim]Br (n=2,4,5,6) was examined. In order to achieve this goal, the “hole theory” has been utilized for estimating the mean radius of hole. According to the hole theory formalism, the mean radius of hole is related to surface tension. To do so, the Fowler recipe of Kirkwood-Buff (FKB) equation is implemented the calculation of Lennard-Jones's contribution to surface tension of ILs. In the following, assessment of the SE equation is depicted by drawing of  versus . Our test confirms the linearity of diagram and then verifies the validity of the aforementioned approach. The results show that within the imidazolium family, as the cation alkyl chain length increases due to the increased Coulombic forces between the cation and the anion, surface tension decreases.