The diffusion in different stages is illustrated as:

• There is a higher concentration of solute on one side of the membrane than on the other..
• Diffusion causes a net movement of solute particles from the side of the membrane with the higher solute concentration to the side with the lower solute concentration.
• Once equilibrium is reached, solute particles continue to diffuse across the membrane in both directions but at approximately equal rates, so there is no net change in solute concentration.