 Okay, so let's try this. It says, what is the mass of mercury produced? So mercury is Hg produced from the decomposition of 1.25 grams of orange mercury-2 oxide. Okay, so we've got the mass of mercury-2 oxide and we want the mass of mercury. Okay, so what's the first thing we need to do? Yeah, we've got to use the molar mass of what? Grams to moles. Grams to moles of mercury-2 oxide, you're saying, right? Right? To convert it to moles, right? Yes. Okay, so has anybody calculated that molar mass yet? What is it? So it's 216.59. Uh-huh, so 216.59. So where would we put that number? On the bottom. 216.59. And I like to put grams of mercury-2 oxide. What would we put on the top? One mole. One mole of mercury-2 oxide. Okay, so look what we have now. We've got moles of mercury-2 oxide. Is that the mass of mercury? No. Not yet. Not yet. We're going to get there. Yeah, very good. So what's the next thing we're going to do? So another step, right? So multiply by what? Molar ratio. Okay, what molar ratio? What's going to be on the bottom? Two moles of what? Mercury-2 oxide. Okay, and at the top? Two moles of mercury. Two moles of mercury. Very good. Okay, so let's cancel and see where we're at now. We're at moles of mercury. Is that the same as mass of mercury, ladies? Is that the same? Mass and moles? Is it the same? No, none are. No, it's not. So what do we have to do to convert from moles to mass? The molar mass. Yeah, that thing, right? So the molar mass of what, though? Mercury. Mercury, right? Where would we get that from? Periodic table. And what does it tell us? We look up there and it says 200. 259. And where are we going to put it? On the bottom or on the top? Top. Top. 200.59. Grams of mercury. Very good. Grams of mercury. And on the bottom? One mole of mercury. Cancel, cancel. Grams of mercury. Is that the mass of mercury? Yes. Wonderful. So we're there. Okay, so let's just calculate this. So 1.25 divided by 216.5 times 200.5. And I get to three significant figures, 1.16 grams of mercury. Is everybody okay doing something like that? Yes. Okay, wonderful. So you've got to remember step by step by step. If you're doing the wrong steps in the wrong order, you're not going to get these problems right. The other thing is we've been having balanced chemical equations given to us. So we've got to remember if it's unbalanced, to balance it first. Okay? Cool.