 Those two to three courses to work, work with when I come. Yeah, I do. That's the best way to do it so we can get down to business, you know, because, I mean, as far as I'm concerned, I'd rather, you know, let's just do some chemistry, you know? I mean, what else are we here to do? You know, let's just do it. OK, so let's try to, I don't know, whichever one. How many molecules of methane are in 48.2 grams of this compound, OK? So methane is CH4, and that's given to you in the problem. And the mass of methane is given to you in the problem, too. Mass equals 48.2 grams. So the first thing you're going to have to do, well, so not given to you is Avogadro's number. You've got to remember that, OK? Yeah, so 6.022. 10 stands in the 23rd. And in this case, it's going to be molecules. Do you know what that equals? 6.022 terms there in the 23rd? Not just Avogadro's. Yeah, one more. That's what you want to think of. You think about Avogadro's number, you know, like people get confused and they're always just writing Avogadro's number, not mole, you know? Because this is important. What it's called, who the heck cares what it's called, you know? It's like I'm teaching all these people chemistry right now. Probably half of them don't even know my name. You're almost coming up, go out now. I know, that's why I said it like that. OK, so let's continue along. So you've got to know this. And that's not given to you in the problem. That's one of the things in chemistry that you have to memorize is that 6.022 turns into the 23rd. So now we're going to find the molar mass of this, OK? The molar mass, remember, that's the mass of one mole. Why is that important? Because one mole, we got that convergent factor and we've got a mass, OK? So we can convert those things now, right? So the molar mass is what we're looking for. What's the molar mass of CH4? So what we're going to have to do is look on our periodic table here. So let's just cut this periodic table goes to many sig figs. But let's just do to four sig figs on each of these, OK? So remember, the molar mass of methane, or CH4, is going to be one times the atomic mass of C plus four times the atomic mass of C times four times the atomic mass of H, like that, OK? So the atomic mass of C, of course, is 12.01 AMU. But we're going to convert this to molar mass, so we'll just do grams per mole, plus four times the molar mass of hydrogen, we'll say. Let's just do that. Hydrogen is that 1.008? Yeah, 1.00 grams per mole. And remember, those numbers are given to you on the periodic table, so it's not anything that you need to memorize. No, I've been doing this so much. I know, right after a while, it's just become second nature to you. So 12.01 plus 16.04. Yeah, four times 1.008 per mole. Remember, this is like the text message way of writing. It's a shortcut, remember, because on typewriters, you can only write things on one line very easily. So you can't do things like one over the other, so it makes it kind of bigger. But in chemistry, we'll want to convert it to that, remember? So this actually equals, for chemistry way that we talk and write things, 16.04 grams divided by 1 mole. And in fact, it's even more than that, right? It's 16.04 grams of methane is 1 mole of methane, right? Does that make sense? OK, so now we've got a conversion factor for methane, right? We've got another one, so we can say 1 mole of methane equals 16.04 grams of methane, right? And we know how many grams of methane we have, so we should be able to figure out how many moles we've got. So let's do that, right? So moles is what we're looking for, so can moles be on the bottom? If that's what we're looking for, if that's the final unit? No. No, it has to be where, on the top. And that's the only thing that we can have. We can't have grams there anymore either, right? No, they've got to go. They've got to go, OK? So let's figure out the number of moles. So n is the variable or whatever that we use for the number of moles, like m for mass or whatever the litter. And so we say the number of moles equals the mass times the molar mass, if you remember that. But you don't have to, because you know all that matters is to convert or to cancel your units out. So the mass of methane that you have is 48.2 grams of methane, right? So if you wanted to, because this is the mass of methane up here. Remember, what did we say over here? We wanted moles over here. Yeah, we got it. So we want to do what to this guy? We want to reverse it. Flip them over, yep, flip them over. One mole of methane, 16.04 grams of methane, OK? So can we cancel something out here? Grams of methane, right? Cancel, cancel. 48.2 divided by 16.04. So we take it to 3 sig figs, which we need to, because that was the only number that was given to us in the problem, right? So it's going to be, in this case, 3.00 moles of methane. But if you don't put those two zeroes there, right, you get some, probably, half a point or something wrong. Yeah, no, I don't understand if you're saying things. Does that make sense to you how to do that? The other thing is like I should have showed you on that density one. Here, if you wanted to remember, I mean, if you are one of these people that desperately needs to memorize stuff, you know what I'm saying, what you should never do in chemistry, right? The formula for the number of moles is the mass times the molar mass, right? Which is what we've done. So mass times the molar mass, right? Or the inverse of that, I guess I should say, one over. See, it's easier when you cancel units out. It just shows you it's easier.