Now, when it comes to osmosis, the solvent moves from a lower concentration solution to a higher concentration solution. Eventually, as it's doing this, equilibrium will be reached, and the net flow of solvent is stopped by osmotic pressure. Osmotic pressure itself is the pressure exerted on the semipermeable membrane by the solvent. If we take a look here, we have these two images. Realize that the blue spheres are our solvent molecules, so think of them as water. And the red ones are our solute molecules. If we look at the image on the left, we can see that there are more red solute molecules on the top portion than on the bottom portion. That means the top part is more saturated, more concentrated. Because of this, remember, osmosis solvents want to move towards the higher concentration. That means that there's going to be greater osmotic pressure on this side here, which is going to force the water to go up towards the more concentrated side. So what's going to start happening is water is going to move through the semipermeable membrane and try to basically dilute this more concentrated portion. So we'd say that the flow of solvent is up.
Eventually, both will be the same concentration. It may not look like it, but just realize the flow of water is going to dilute the top part, so it's going to be more volume per the same number of solute molecules. As a result of this, the pressure on both sides of the semipermeable membrane, this membrane, are going to be equal in force. So there's not going to be a net flow of water. We're going to say here that the flow of solvent, the net flow, would be 0. Right? We're going to say that there's not going to be a big change. Water is still flowing both ways, but one side is not gaining more water than the other side. So there's not a net change in volume for either side. So just remember, it's osmotic pressure that's going to stop this movement of water more so to one side than the other. This happens when the concentrations of both sides reach the same value. Initially, the more concentrated side is going to be diluted by the less concentrated side.