 Okay, let's try to do this one. So it says a balloon at STP is filled with helium gas. The balloon is filled with exactly 20 grams of helium. Calculate the volume of the balloon, okay? Up in the place where the conversion factors and other useful information, it says one mole of any gas at STP is 22.4 liters, okay? So that means is helium a gas? So one mole of helium is how many liters? 22.4, right? Okay, so let's read the question again. It says a balloon at STP is filled with helium gas. If the balloon is filled with exactly 20 grams of helium, calculate the volume of the balloon. Can you get moles from that information? Yeah. Where's it back? You got the mass of helium, right? So the mass of helium, it said was what? 20 grams, right? 20.0 grams, actually. And how do we convert grams to moles? Well, what is that thing called? We talked about it just 10 seconds ago next door. The molar mass. Molar mass. Right? So what is the units of molar mass? Per mole. Per mole, right? So would that be able to convert grams to moles? That's all you got to do, right? So the number of moles of helium, 20.0 grams. So you want to put what on the bottom? Moles. Grams. Moles on the top, right? So one mole. How many grams is that? How would you figure that out? Got to look at the periodic table, right? That's all. For every one mole of helium, it says it's 4.003 grams. So what do we do now? Cancel, cancel. Gives us the number of moles. Do you have a calculator? Okay. So let's just take 20 divided by, well, this one we probably could have done in our head, 4.003. To the right number of sig figs is going to be 3, right? This says in our calculator 4.99625281, right? So it's a three sig figs, that's going to be 5.00, okay? So 5.00 moles. Is that what we were looking for? It said calculate the volume of the balloon. No, that's not the volume. So do we have a conversion factor that relates moles of helium to the volume? Yeah. So what's the volume? And well, let's just do the volume in liters. It didn't specify what kind of units it wanted, right? So how would we do that? 5.00 moles of helium, and then we got to have a conversion factor that converts moles to liters, right? Do we have that? Yes. One mole of helium is 22.4 liters. When we do that, I'm just going to use that 4.999 figure. When we do that, remember three sig figs, that says 111.9, so that's going to be 112. 112 liters. So if you want to look at what you did, you tried to do all this P vehicles NIT stuff. But it was given to you that conversion factor, right? And all that you needed to do, this is chapter three stuff. All you need to do is take grams and convert it to moles, and then one more conversion factor. Are there any questions on that one that you would like to? Yeah, I just did the wrong thing. Yeah.