 OK, we'll do this one for the last problem of the day. It says, if 10.11 grams of limestone decomposes by heat to give 8.51 grams of solid calcium oxide and carbon dioxide gas, what is the mass of carbon dioxide produced? So we don't know at this point what calcium oxide is. We don't know what limestone is, and we don't know what carbon dioxide is. Because we're in introductory chemistry, and we just haven't learned that stuff yet. But we do know the law of conservation of mass. So the stuff that's at the beginning of the reaction and the stuff that's at the end of the reaction passed away the same amount. So we could draw up a crude reaction diagram. So we can say, well, we took limestone, and that was the only thing that we had in the starting material. Do you guys remember? It said we just had limestone, and we heated it up, right? So we heated it up, and it decomposed to what? Calcium oxide plus carbon dioxide. Does everybody agree with what I've written there? Does that make sense to write it like that? So I want you to practice doing this type of stuff. You're going to need to do these for these law of conservation of mass problems. So it gave us the initial mass of limestone at 10.11 grams. It gave us the amount of calcium oxide that was produced, 8.51 grams. And it wants us to know, well, how many grams of carbon dioxide did we produce? So remember, law of conservation of mass says the reactants mass has to add up to the products mass. So the total reactants has to equal the total products. Does it equal that right now? So does 10.11 equal 8.51? So we need that mass of carbon dioxide to make it equivalent here. Does that make sense? So in other words, the mass of the reactants has to equal the mass of the products. Is that OK with me writing like that? So the mass of, we'll say, the limestone has to equal the mass of the calcium oxide plus, right? Does that make sense? The mass of what? Help me out. Carbon dioxide. Dioxide, yes. Thank you all for helping me out. So can we do this together? Can we try this one together? So we want the mass of the carbon dioxide, right? So we need to rearrange this equation. Do you remember your algebra to rearrange your equations? So we're going to rearrange this to say, what? We're going to subtract mass of calcium oxide from both sides. So in other words, we're going to say the mass of the limestone minus the mass of the calcium oxide equals, well, we could say, mass of calcium oxide plus, mass of carbon dioxide minus mass of calcium oxide, which would cancel that out, right? So it would equal the mass of the carbon dioxide. Does that make sense? OK. So now let's just plug in numbers, OK? So what's the mass of the limestone? 10.11 grams. 10.11 grams. Remember, we have to use those units. And the mass of the calcium oxide, what is that? 8.51 grams. 8.51 grams, OK? So now, get out of your calculators, because you need to use your calculator for this. Unless you can do that in your head, which you might be able to do, 10.11 minus 8.51. And it's 1.60 because there's two spaces after the decimal. 1.60 grams of carbon. Any questions on that one? So you're going to have to learn how to do those problems, OK? So I'll post this video up there tonight. You'll watch it a few times, OK? There's a few conservation of mass problems up there. All right. Any questions on this one? Can I kill it?