 Okay. Yeah. So with this problem, if 5.0 grams of helium is added to a 1 liter balloon containing 1 gram of helium already, what is the new volume of the balloon? So the number of moles initially actually is going to be 1.0 grams. Okay? So we're going to have to figure out the number of moles by taking 1.00 grams and multiplying it by the inverse of the molecular weight of helium, which is 1 mole divided by 4.00 grams. Grams cancel and we get 1 divided by 4, which is 0.25, right? 0.250 moles. Okay? So that's going to be the initial number of moles. But 5 grams is added to 1 gram. How many grams do we have now? 6 grams. The final number of moles is going to be 6.00 grams because this is 5 plus 1. 6.00 is 5.00 plus 1.0 multiplied by the inverse of the molecular weight of helium, just like last time. 6 divided by 4. 1.5. Let's get some room here. Can I erase this, ladies and gentlemen? Ladies and gentlemen? These are the only variables that we've got, right? It must be off of us a lot because we could erase all the other variables, right? What we've got to do is isolate Vf, which is right here, and then solve for it. So the first thing we want to do is in so, sorry, we're looking for Vf, so we just got to get rid of Nf, right? So we just multiply both sides by Nf. Nf will cancel there, and we'll get back to equation. So the new equation is Vf equals Nf times Vi over Nf. Does that make sense? Okay? And now all we do is plug in stuff. So Nf is 1.50 mole, Vi is 1.00 mole of liters divided by 0 liters. Of course, liters cancel should be moles. Moles cancel, right? That makes more sense. Since we're looking for a volume, so we could have figured that out by knowing that we're looking for a volume. So 1.5 times 1 is 1.5 and divided by 0.25, 6.0. Volume and number of moles are also proportional to each other. So if you increase the number of moles, you should also be increasing the volume, okay? So if you get some answer that's less than your initial volume, then you know you've done something wrong, okay? So if you add more to it, the volume's going to increase. So this is Alpha-Gatros law solving for Vf.