Molecular association contribution to self-diffusion in a chloroform – methanol system

Self-diffusion of components of a binary chloroform – methanol system has been investigated by experimental (pulsed gradient spin-echo nuclear magnetic resonance (PGSE NMR)), molecular dynamics (MD) simulation and theoretical (athermal associated solution model) methods at 298 K. The concentration dependences of the effective hydrodynamic radii of the mixture components calculated on the basis of the Stokes-Einstein equation are shown to be extremal, which indicates molecular association in the system. The analysis of the radial distribution functions and the fraction of molecules of chloroform and methanol with i-hydrogen bonds obtained from MD simulations made it possible to determine the degree of self- and heteroassociation of the mixture components. The contributions of self-association and heteroassociation to the self-diffusion of the mixture components are estimated within the framework of the athermal associated solution model, taking into account the Stokes-Einstein equation.