Relation Between the Diffusivity, Viscosity, and Ionic Radius of LiCl in Water, Methanol, and Ethylene Glycol: A Molecular Dynamics Simulation
详细信息 查看全文
- 作者：Parveen Kumar ; Srinivasa R. Varanasi ; S. Yashonath
- 刊名：The Journal of Physical Chemistry B
- 出版年：2013
- 出版时间：July 11, 2013
- 年：2013
- 卷：117
- 期：27
- 页码：8196-8208
- 全文大小：597K
- 年卷期：v.117,no.27(July 11, 2013)
- ISSN：1520-5207
文摘
A molecular dynamics (MD) investigation of LiCl in water, methanol, and ethylene glycol (EG) at 298 K is reported. Several structural and dynamical properties of the ions as well as the solvent such as self-diffusivity, radial distribution functions, void and neck distributions, velocity autocorrelation functions, and mean residence times of solvent in the first solvation shell have been computed. The results show that the reciprocal relationship between the self-diffusivity of the ions and the viscosity is valid in almost all solvents with the exception of water. From an analysis of radial distribution functions and coordination numbers the nature of hydrogen bonding within the solvent and its influence on the void and neck distribution becomes evident. It is seen that the solvent鈥搒olvent interaction is important in EG while solute鈥搒olvent interactions dominate in water and methanol. From Voronoi tessellation, it is seen that the voids and necks within methanol are larger as compared to those within water or EG. On the basis of the void and neck distributions obtained from MD simulations and literature experimental data of limiting ion conductivity for various ions of different sizes, we show that there is a relation between the void and neck radius on the one hand and dependence of conductivity on the ionic radius on the other. It is shown that the presence of large diameter voids and necks in methanol is responsible for maximum in limiting ion conductivity (位0) of TMA+, while in water and EG, the maximum is seen for Rb+. In the case of monovalent anions, maximum in 位0 as a function ionic radius is seen for Br鈥?/sup> in water and EG but for the larger ClO4鈥?/sup> ion in methanol. The relation between the void and neck distribution and the variation in 位0 with ionic radius arises via the Levitation effect which is discussed. These studies show the importance of the solvent structure and the associated void structure.