DIFFUSION IN BINARY LIQUID MIXTURES

Several expressions previously proposed for the mutual diffusion coefficient of a binary liquid system are shown to follow from the Bearman theory when a geometric-mean relationship between certain friction coefficients is assumed. The Rice-Allnatt extension of the Rice-Kirkwood theory, which can be tested without the introduction of this assumption, is shown to give virtually quantitative agreement with experiment for both viscosity and diffusion when the binary system is close to ideality. Under these conditions, however, their equations likewise approximate closely to the assumption of a geometric-mean relationship between the friction constants.