Solubility

Solubility, s, is used to define the “normalized concentration,” $\varphi$, of the diffusing phase in a mass diffusion process:

where c is the concentration. The normalized concentration is often also referred to as the “activity” of the diffusing material, and the gradients of the normalized concentration, along with gradients of temperature and pressure stress, drive the diffusion process (see Diffusivity).

SOLUBILITY