14. Solutions
Osmosis
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Alright, everyone. So at this point, we can say that the solvent moves from a lower concentration solution to a higher concentration solution. And eventually, equilibrium is reached and the net flow of solvent is stopped by osmotic pressure. Now, what exactly is osmotic pressure itself? Well, it's the counter force required to stop the flow of solvent through the semi permeable membrane. So let's pretend that my hand is this semi permeable membrane. And we have the flow of water on this side is less concentrated. Over here, on the other side of the semi permeable membrane, it's more concentrated. Water is going to want to flow through this semi permeable membrane to the other side. Now, as water is flowing through, there's going to be some resistance. There is a pressure that's on this side of the semipermeable membrane. That pressure is osmotic pressure. So the solvent's passing through the semipermeable membrane, trying to go from the less concentrated solution to, to the more concentrated solution. But my osmotic pressure that's building behind here is trying to stop the flow of water or the flow of solvent. K. So that's what osmotic pressure is. It's the counterforce that's pushing against the sulfur that's coming through the semiperlable membrane. Now if we take a look here at this image, we have these little blue spheres which represent our solvent molecules. And then we have our solute molecules. If we take a look at our two images, we can see in the top part, we have how many solute particles. We have 1, 2, 3, 4, 5, 6, 7 of the solute particles. And then we only have 3 solvent. Then if we look at the bottom part, we have what? 2 solute. And we see that we have way more solvent a ton. So actually let's count. We have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15. Right. So we have 15 solvent. We We didn't really need to count. We can already see there's way more solvent than solute. So we can say that the bottom part is the part that is less concentrated because there's way more of our solvents there. So it's it's the lower concentration solution. The top part has way more solute than solvent, so it's the more concentrated or higher concentration solution. So that means water is gonna flow naturally from the less the lower concentration side to the higher. So water is gonna move this way. As it's moving through this semiperbal membrane here, remember there's gonna be that force that's kind of trying to stop the flow of water. That's the osmotic pressure. It's building on this side here. Because remember, what's the ultimate goal of osmosis? The ultimate goal of osmosis is to get both sides to have the same equal solution concentrations. And we're gonna say the bigger the difference in solution concentrations on both sides, then the higher the osmotic pressure needed to stop the flow of solvent. Right? So that's what we'd say in terms of this particular image. If we go to the other side, what do we see? Well, if we go to the other side we have 1, 2, 3, 4, 5, 6, 7 solute. And then solvent, we have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, which is basically a 1 to 2 ratio. One solute for every 2 solvent. If we look here, we have what? We have 2 solute and 4 solvent. The numbers are smaller, but if we are paying attention here, we can see if the ratio is still the same. It's still a 1 to 2 ratio. It's still a 1 solute for every 2 solvent. So although numbers look different, the ratios are the same. So the concentrations on both sides are the same. K. So we'd say that there is no net flow between the 2 because both sides already have equal con solution concentrations. Right. So here we wouldn't talk about the flow of solvent. Alright. So just remember, this is what we're talking about. Osmosis is the flow of water from a lower concentration or less concentrated side to a more concentrated side. And as it's passing through the semipermeable membrane, there's an osmotic pressure that's kind of trying to stop that flow of solvent.
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