CRITICAL-BEHAVIOR OF THE SELF-DIFFUSION COEFFICIENT IN A BINARY FLUID

The method of the open-ended capillary tube has been used to determine the self-diffusion coefficient of the Na-22+ ion in an isobutyric acid, water, and a 10(-3) M NaCl critical mixture. The experimental range of temperature is 0.360 less-than-or-equal-to T-T(c) less-than-or-equal-to 9.860-degrees-C. This study is a preliminary step in the investigation of ion-transport phenomena in binary fluids. We find that in the critical region the Arrhenius law has an important deviation and the self-diffusion coefficient D(cm2/s) can be governed by the mean-field theory.