The Variation of the Differential Diffusion Constant of Hydrochloric Acid with Temperature

The differential diffusion constant of hydrochloric acid has been determined at temperatures ranging from 10°C to 35°C. At 10° and at 15°, the variation of the diffusion constant with concentration is given by the relation ${\mathrm{k=k}}_0\text{(1+c∂}\ln {\mathrm{f/\partial c)·(\eta }}_0\mathrm{/\eta )}$ only up to about 0.2 normal. The activation energy of diffusion for concentrations less than 0.2N is practically independent of acid concentration; it decreases with increasing temperature, and is of the order of magnitude of the activation energy of viscous flow. For higher concentrations, the activation energy increases with increasing acid concentration.