ABSTRACT
When the transport of ions or molecules occurs in the absence of bulk flow it is called diffusion. Substances will spontaneously diffuse toward the region of lower chemical potential. This transport or flux of matter is represented by Fick’s first law and is proportional to the concentration gradient. This is represented by:
J D c xix i= − ∂ ∂( ) (6.1)
where: Jix = flux of component i in the x direction, D = diffusion coefficient, and ci = concentration of component i.
