Why Diffusivity( AB) **t equal to the diffusivity ( BA) in the liquid phase ?
 

Why Diffusivity( AB) **t equal to the diffusivity ( BA) in the liquid phase ?
I have a question ,
why the diffusivity (AB) **t equal to the diffusivity (BA) in the liquid phase ?
While ,they are equal only for gas phase

A and B are any liquid component