# The Mutual Diffusion Coefficient of Ethanol-Water Mixtures: Determination by a Rapid, New Method

K. C. Pratt, W. A. Wakeham

## Abstract

Mutual diffusion coefficients for liquid mixtures of ethanol and water have been measured over the entire range of composition and for temperatures from 25 to 65 degrees C at a pressure of 1 bar (10$^{5}$ Pa). At the lowest temperature, the results establish the validity of a new experimental method based upon Taylor's analysis of solute dispersion in laminar flow. The method offers advantages of simplicity and speed over other techniques, and allows direct measurement of diffusion coefficients at well-defined mixture compositions. The experimental data have an estimated uncertainty of $\pm$2.5%. The results have been utilized to evaluate friction coefficients arising in the statistical mechanical theory of transport in liquid mixtures.