What role does Brownian motion play in diffusion?

Answer 1

Brownian motion keeps the molecules moving so that they can go from areas of higher concentration to areas of lower concentration, until equilibrium is reached.

Answer 2

Brownian motion is the random movement of molecules and really tiny particles (they are getting bumped around by molecules around them).
Higher temperature results in more movement of molecules. Cooler temperature-->less movement.
Diffusion is when molecules mix because of these random movements.
Imagine you have a box. Put yellow beads at one end of the box and red beads on the other end of the box. These beads represent molecules. If you leave it as is, nothing happens. This is like if the temperature is at abolute zero (coldest theoretical limit). There is no diffusion. Now simulate Brownian motion by shaking the box. Each bead moves randomly. After a while, the red and yellow beads are mixed-- diffusion. If you shake it harder, this happens faster--higher the temperature--greater the rate of diffusion.

Answer 3

here go to this link and Read this article it may help you.

http://en.wikipedia.org/wiki/Brownian_motion