 Okay. Let's do this problem. What is the freezing point of a solution that is made by dissolving 114 grams of the non-electrolyte glycerol C3H8O3 and 1,000 grams of water? Okay. This problem, and then it gives you some information about water. What's the freezing point of water and what's the KF of water? Okay. So, it's asking what's the freezing point of the solution? So, how do I go about doing this? Well, the first thing, of course, you're going to want to do, well, you've got the mass of glycerol. This is going to be your solute 114 grams. In fact, what you're going to want to do, it's asking, this is actually essentially a freezing point depression question. So, it's asking you, well, the freezing point depression formula is delta Tf equals Kf times m. This m here, remember, is molality, molality. So, that's of the solute or the solution. So, that's going to be the number of moles of solute over the mass in kilograms of the solvent. So, we got the mass of glycerol and that's the solute, but we don't know the number of moles of it. Okay. So, how do we figure out the number of moles? Number of moles of the solute is going to be 114 grams times something that's, of course, moles per gram. That's the inverse of the molecular weight. What's the molecular weight of, or the molar mass, I mean, of C3H8O3? Well, it's 3 times C plus 8 times H times O. And when I multiply all that out, I got 92.09 grams per mole, like that. So, if I just flip that over, I'll get moles per gram, right? So, 1 mole per 92.02 grams, cancel, cancel. And I just take 114 divided by 92.02. I get the same number as I got before, 1.24 moles. Okay. So, that's the number of moles of solute that you got. But you still don't have the mass of the, in kilograms of the solvent, but you do got the mass of the solvent. Water is the solvent, 1000 grams. That's this. Well, how do we convert grams to kilograms? Okay. 1000 grams is one kilogram. So, now we can go over here and plug in these numbers to get the molarity, or the molality. So, we got 1.24 moles divided by 1 kilogram. When we do that, we get 1.24 mol. Okay. So, that's the molarity or the molality of the solution. But that doesn't tell us what we want to know, because it's asking us what's the new freezing point of the solution. Okay. So, we've got to take that number and plug it into this equation now. I'm going to erase this stuff. Okay. So, we've got that equation, delta tf equals kf times m molality. kf is given to us up there, kf 1.86 degrees Celsius per molal. Okay. So, we just plug those numbers in. 1.24 molal. Cancel there, cancel there. And what we get from doing that, 2.03 degrees Celsius. Okay. So, that's just the change in the freezing point. It's asking us what the new freezing point is. So, the delta t, oh, sorry, it is 2.30. 2.30. That's my dyslexia going on. Okay. So, that's delta tf. So, we go tf nu, because it's asking us what the new freezing temperature is. Well, that's going to be the original freezing temperature minus the change in freezing temperature. Why? Because this is freezing point depression. So, it means it's going down. Okay. Right? So, you know it's got to be this way. So, the original freezing point was zero, well, 0.00 or whatever. It doesn't give you any sig figs. So, you can use as many as you want. Minus 2.30. So, the new freezing temperature is going to be negative 2.30 degrees Celsius. Okay. The molality, yeah. You're going to learn tomorrow or on Wednesday. Okay. So, does it make sense going through it like this? Okay.