Linear response theory of the heat of transport of electrolyte solutions: Electrostatic contributions

摘要

The electrostatic contribution to the heat of transport of very dilute electrolyte solutions is determined from the linear response theory. The model considered is that of charged hard spheres immersed in a medium of solvent molecules which screen the Coulomb potential between ions by the dielectric constantD. Furthermore, we assume that the fluctuation in phase that determines the momentum of the ion is just the Brownian motion. The Brownian motion approximation simplifies the calculation and enables us to evaluate the time integral. The Brownian motion approximation also effectively decouples the various diffusion fluxes and thus the contributions of the cross coefficients to the heat of transport are not calculated in this treatment. The limiting slope for the heat of transport predicted in an earlier work by Helfand and Kirkwood lsqb;J. Chem. Phys. 32, 857 (1960)rsqb; agrees with ours in the limit where the hard sphere diameter sgr;rarr;0.