 Okay, so this one says how many grams of sodium chloride do you need or are needed to produce 9.21 liters of oxygen gas, okay? So we have the number 9.21 and we're going backwards to figure out well what was the mass that we had to begin with, okay? So it's the first thing we're going to have to do to convert from liters to moles, right? So this is at STP, so we've got that conversion factor that was given to us up there, right? For every 22.4 liters of oxygen gas, we've got one mole of oxygen gas, okay? So watch, cancel, cancel and we're at moles of oxygen gas. But we want to get to massive sodium chloride, so we're not there yet, right? So what do we use? Next. What's next? So we're going to get from moles to moles, so what is that called? Mole ratio. Mole ratio, so which mole ratio are we going to use? We want to get to sodium chloride eventually, so what are we going to use? On the top, what? 2. 2. 2. 2. 2. 2. 2. 2. 2. 2. 2. 2. 2. 2. Mole of sodium chloride? Okay, now what do we want to do? Convert it to grams. Convert it to grams, and how do we convert from moles to mass? Yeah. The moles are mass, very good, okay? So, how do we figure out what the moles are mass? Well, what mole are we going to be using? Sodium chloride, okay? Let's figure that out together. So 22.99 plus 35.45 plus 3 times 60. So at the bottom, we're going to put what? One mole. One mole. Sodium chloride. Very good. Sodium chloride. And on the top, I got 106.44 grams of sodium chloride. OK? Cancel. Cancel. And are we at mass of sodium chloride now? Yes, we are. So we should be able to just convert now. So I want you guys to try it on your calculators. Make sure you get the same answer as me. The two Sukfugs, 29.22 grams of sodium chloride. So hopefully you guys got the same. If not, you probably punched it into your calculator incorrectly. Are you impressed with yourself? Yes, you should be. I'm proud of you all. All of you guys, OK? If you're able to understand this, I'm real proud of you guys, OK?