What is Fick’s Law equation?

Fick’s Law is a fundamental equation in the field of diffusion that describes the rate at which a substance diffuses through a medium. It states that the flux of particles (J) is proportional to the negative concentration gradient (dC/dx) and the diffusion coefficient (D). The equation is given by:

​$$J=-D\frac{dC}{dx}$$

where:

• J represents the diffusion flux, which is the amount of substance that diffuses per unit area per unit of time.
• D is the diffusion coefficient or diffusivity, which is a constant that depends on the properties of the diffusing species and the medium through which it is diffusing.
• dC/dx denotes the concentration gradient, which is the rate of change of concentration with respect to distance.

In simple terms, Fick’s Law states that the diffusion flux is proportional to the concentration gradient and the diffusion coefficient, and it occurs from areas of higher concentration to areas of lower concentration.