 OK, so this is a problem that we'll be doing that uses the ideal gas law but also integrates the chemical equation in association with it. OK, so the problem itself says acetylene burns via the following balanced chemical equation, and that's given to you on the board. If you have 10.0 liter tank of acetylene at 25.0, degrees Celsius, and 100.8 m of pressure, how much carbon dioxide will you form if you burn all the acetylene in the tank? OK, so in order to do this problem, well, this is nice enough that liters is already in the units that we want, or the volume is, and the pressure is already in units of 8 m. So those are units that we would like to. So what we're going to do is add 273 to this. OK, so the other thing we have to remember, well, is the ideal gas equation in order to do this. Why? Because we need to know the number of moles of acetylene that we're starting with. OK, acetylene is this C2H2. So what is the ideal gas law? PV equals nRT. What are we solving for? n, number of moles. So solve for n, that's going to be PV over RT. Like that. Everybody OK with that? OK, so now we just take these numbers. OK, remember, R, that's given to us 0.0821 liter 8 m under 8 m and 0.0 liter divided by R, 0.0821 liter 8 m per mole kelvin times temperature 298.0 kelvin. Is everybody OK with writing something like that? So now let's cancel our units, OK? So ATM cancels with ATM, liters cancels with liters. Kelvin's on the bottom down here. So cancels with kelvin there. So 1 divided by divided by puts it up to the top, right? So moles is our new unit. Is everybody OK with that kind of assessment? So our unit is going to be moles. And it looks like it's going to be three sick things. So now all we do is just plug these numbers into our calculator and that will give us the number of moles of acetylene that we got. So 100 times 10 divided by 0.0821 and divide that by 298. And the number of moles that I receive to three sick things is 40.9 moles of acetylene. So that's just like a normal PV equals NRT calculation, like the ones we were doing downstairs, OK? So let's just write down that number of moles because I'm going to have to erase them in order to do the rest of the problem. So is everybody OK if I erase this bottom part? Anybody still writing? They're wonderful. You guys are fast writers. But the problem didn't ask for what is the number of moles of acetylene, right? It asked us how much carbon dioxide will you form if you burn all those acetylene in the tank? So how much, to me, implies number of moles, OK? If it would have said the mass, then we would have had to convert that number of moles to something like grams or something like that, OK? So in other words, number of moles of acetylene we have is down here at 40.9. But we're looking for the number of moles of carbon dioxide. Does everybody understand what I've done here? So now, not only have we used the PV equals NRT, now we're going to integrate that with the chemical equation, OK? So the number of moles of carbon dioxide is going to equal the number of moles of acetylene. And you've got to convert that using the values on the chemical equation. So carbon dioxide is what we want. So we're going to put that up here. So four moles of CO2 will be formed for every two moles of C2H2 we use. So moles C2H2 cancel out. So what are we going to do? Multiply this by 2, right? So times 4 divided by 2. So that's going to give us, what is it, 81 point. So everybody OK with doing something like that? So again, you have to recall what we learned, I think, in chapter 3 or something, that the chemical equation shows us the molten mole ratio. And then, of course, also what we've learned in this chapter about the PV equals NRT. So for this, you're going to have to convert things to moles to do. Any questions on that one? Again, I have a few more of these exact type of problems already recorded. Feel free to watch those as well.