 Okay. So let's record this video. What do you say? Since it's recording, let's record it. Okay. So we're going to do that same problem that we just did the hard way. Okay? So how many moles of oxygen are in 12.23 grams of water? Well, the first thing we need to do is figure out the molecular weight of water. We did that earlier, so I didn't erase it, so I would have to do it again. But you can see there. Pause the video if you want. Okay. Now what we need to do is convert gram, our AMUs, to grams. Okay? So to figure out the mass of water that we have, the mass of one water molecule. How do we do that? We take 18.02 AMU and multiply that by our conversion factor that we recall just a second ago. 1.661 times 10 to the negative 24th grams equals 1 AMU. It's a very small number. Okay? So we just take that conversion factor, put AMU on the bottom, right? And we get the amount of AMUs to cancel out. 1.661 times 10 to the negative 24th grams. AMUs cancel. And we get the mass in grams of one water molecule. I got 2.9912 times 10 to the negative 23rd grams. That's how much one water molecule weighs. Okay? So now we've got to figure out, so this is how many grams we can even write per water molecule. We could, and we could say here, 18.02 AMU per one water molecule. And that's where that unit would have come from. It'll make it easier in a second. This is why I'm doing this. So let's now figure out the mass of one mole of water molecules. Okay? So how do we do that? So the mass of a mole of water. We know how much it is for one water molecule. How many grams? So 2.99312 times 10 to the negative 23rd grams for one water molecule. Avogadro's number, right? 6.022 times 10 to the 23rd water molecule. That equals one mole, right? So we can divide that by one mole. How is this confusing? How many things is a mole? How many items? How many units? 6.022 times 10 to the 23rd, right? Okay? So we've got now, we can cancel out this water molecule with that, right? And that gives us grams per mole, right? And that was something we got just by looking at this earlier. So let's do all this calculation, okay? So let's get that number and see if it's 18.02. Okay? So multiply that by 6.02223. What do we get? 18.02. Oh, two. Oh, four, five or whatever. Grants of water. That's amazing, huh? How does that work? All we've got to do is do all the other calculations that we did before, okay? So we're going to have to erase all this business because I don't have enough room. So can I erase? Is everybody cool with me erasing? How many moles of oxygen are in each mole of water? How many moles of oxygen per mole of water? One. One to one, right? One mole of oxygen to one mole of water. So, we also know that we've got 12.33 grams of water. So the number of moles of water that we're going to have is going to be 12.33, our 12.23 grams of water, divided by 0.245 grams. So we're going to give us mole of water, right? So 12.23 divided by 6.7852. Sorry, moles of water. And then we need to figure out the moles of oxygen. And so we're just going to take that number, 0.7852 moles of water. So this conversion factor, one mole of water, one mole of oxygen, moles of water canceled out. And we get 0.67, we've got to take this to two significant figures, I mean four significant figures, 0.6785 moles. And that should be the same number as we got before, right? Is it?