 Okay, so let's try this one. It says how many grams of oxygen are found in 42.3 grams of C6H12O6? Okay, so This is the stuff that's given to you. Remember the first thing we need to do is find the molar mass of C6H12O6 Okay, so when we do that So you found it earlier right? It was 180 0.16 grams per mole Okay, the other thing if we look at the periodic table over there, right? It says that the atomic mass or the atomic weight of Oxygen right is going to be 16, we'll say the molar mass of oxygen is 16.00 grams per mole Okay, these are actually all the stuff you need to know to be able to do this problem Okay, and we're going to do it all at once. Okay, so the mass of oxygen That's going to equal well the mass of the C6H12O6 So 42.3 grams of C6H12O6 And it's good to kind of keep your space, you know with writing those Molecular formulas here. We got the molar mass. So Remember we want to get rid of grams. So we're going to put that at the bottom 180.16 grams of C6H12O6 And we're going to have one mole of C6H12O6 This one works a little better So when we do that Cancel, cancel like that. Now we're in moles of C6H12O6. So for every one mole Of C6H12O6 we have six moles of Oxygen like that. I'll just go back and forth I guess both of these pins So we're going to cancel, cancel and then moles of oxygen We've got grams of oxygen over there. So we just say for every One mole of oxygen equals 16.00 grams of oxygen like that And that will cancel and cancel like that. So what does that equal? It should be From all we cancel it out the grams of oxygen. Okay. Does that make sense? Okay, so let's get our calculator sound and say 42.3 divided by 180.16 Multiply that number by 6 and then multiply that number by 16 and to three significant digits we get 22.5 grams of oxygen Okay, yeah, so you could do it by a mass percent, you know, it's but this way it's much easier Okay Yeah, I think it's more more, you know, accurate. It's straight. Yeah, it's straightforward. You're right. It's more accurate as well Okay It's doing exactly what you've learned how to do just cancelling out the units So as opposed to trying to do it all the other way, you know, okay wonderful. Let's go