In a phase with uniform temperature, absent external net forces acting on the particles, the diffusion process will eventually result in complete mixing.Д¬onsider two systems S 1 and S 2 at the same temperature and capable of exchanging particles. Since the molecules are still in motion, but an equilibrium has been established, the result of molecular diffusion is called a 'dynamic equilibrium'. The result of diffusion is a gradual mixing of material such that the distribution of molecules is uniform. Once the concentrations are equal the molecules continue to move, but since there is no concentration gradient the process of molecular diffusion has ceased and is instead governed by the process of self-diffusion, originating from the random motion of the molecules. Diffusion explains the net flux of molecules from a region of higher concentration to one of lower concentration. The rate of this movement is a function of temperature, viscosity of the fluid and the size (mass) of the particles. Molecular diffusion, often simply called diffusion, is the thermal motion of all (liquid or gas) particles at temperatures above absolute zero. Bottom: With an enormous number of solute molecules, all randomness is gone: The solute appears to move smoothly and systematically from high-concentration areas to low-concentration areas, following Fick's laws. Middle: With more molecules, there is a clear trend where the solute fills the container more and more uniformly.

Top: A single molecule moves around randomly. The barrier is removed, and the solute diffuses to fill the whole container. Initially, there are solute molecules on the left side of a barrier (purple line) and none on the right. Diffusion from a microscopic and macroscopic point of view.

Concentration gradient