So notice we had no molecules A on the right side. And so A will move naturally from this location to this location. And likewise the B molecules will move down their concentration gradient from a higher concentration to a lower concentration in the opposite direction of A. And eventually we will have an equilibrium that will exist and our concentration gradient will basically cease to exist. Now, according to Brownian motion, molecules A and molecules B will still move across our semipermeable membrane, but there will be no net change. So we take six molecules A and place them on the left side of a fluid filled container.