Now, separating the left side from the right side is a semipermeable membrane. And the semipermeable membrane has small pores that allows the movement of water molecules but does not allow the movement of these solute molecules. So the green dots cannot actually move across the semipermeable membrane. But the water molecules not shown can actually move across the semipermeable membrane. Now, from this discussion above, we know pure water has a potential, an osmotic potential of zero. But this water that contains the solute molecules has a smaller, a more negative osmotic potential.