 Okay. Okay. So let's try this one here. Okay. Determine the change in volume that takes place when a 2 liter sample of nitrogen gas is heated from 250 degrees Celsius to 500 degrees Celsius. Okay. So we, oh, we do know the initial volume here. So let's write down your variables here. First, volume, temperature, volume initial, temperature initial, volume final, temperature final. And for Charles Law, of course, is going to be a relation between volume and temperature in these variables here. So the first thing you do is plug in the initial volume. Well, that's 2.0 liters. The initial temperature is 250 degrees Celsius, but let's always, for ideal gas laws, change the temperature to Kelvin. Okay. Always change it to Kelvin. In this problem, you don't necessarily have to, but I think if we get into that habit, it'll be good. So remember, to change something and to Kelvin, you just add 273 to it if it's in Celsius. New temperature initial is 523 Kelvin. The final volume, well, that's what we're trying to figure out where it says the change in volume. So we don't know that one. And then the final temperature, of course, is going to be 500 plus 273. VF is already on this side of the equation. So we want to get rid of the other things that are on that side of the equation. Of course, that's Tf, right? Tf is being divided by Vf. So we've got to multiply by Tf. Okay. That cancels Tf's out. And of course, we've got to multiply by Tf on this side of the equation as well. That's whatever we do on one side of the equation. We've got to do on the other side of the equation. So our new expression now is Vf equals Tf times Vi over, all we do is just plug in these numbers. So Tf, 773 Kelvin, that's guys. Because then you can see what cancels at the end. Vi, of course, is 2.0 liters divided by Ti, which is 523 Kelvin. Plug those numbers into your calculator. So Kelvin cancels, right? And we're going to get liters. And my final answer to 3 safe figs, since all of our initial had 3 safe figs, we want our final answer to have a 3 safe fig. I got 2.96 liters as the final answer. So you can see here that when you heat something up, right, it increases the volume. Okay? So when you heat something up, it increases the volume so they're proportional to each other.