 Okay, so let's try this problem. It says, determine the amount of heat in kilojoules given off when 1.26 times 10 to the fourth grams of nitrogen dioxide are produced according to the reaction equation. And then it gives you the heat per mole produced, okay? So here, it tells you the mass of nitrogen dioxide, okay? In order to use this chemical equation, remember we have to convert things into moles, okay? So the first thing we're going to have to do is convert this mass into moles. So how do we do that? Do you remember how to do that? Use the what? What's the? The molar mass. Yeah. Okay, so what would be the molar mass of nitrogen dioxide? 46.01 grams per mole, okay? So remember we talked about that, okay? So to figure out the number of moles of NO2, that's what we do. We go 1.2 thick times 10 to the fourth grams of NO2. So that's what we start out with. You said what do we have? 46.01 grams of NO2 per every one mole of NO2. Does that make sense? Yes. Okay, so then we cancel those out. That will give us the number of moles of NO2 that we've got, right? So let's do that together. So 1.26 to the fourth divided by 46.01. And I'm just going to keep this at three six big, so 274 moles. That's a lot. Yeah. Okay, so the other thing we know, remember from the chemical equation, we can use these coefficients as a one there, right? To convert from one to the other. But we can also use this number as a conversion factor for those as well, okay? So what we have here is for every two moles of nitrogen dioxide, right? Does that make sense? That equals this amount of heat given off, okay? So we've got negative 114.6 kilojoules per mole, like that, okay? So for every two moles, we give off 114 kilojoules, okay? So it would be the same thing if we use that amount. So let's just put that in here, okay? So now it wants us to figure out, well, what's the energy given off if we've made that many, if we've made this much grams, okay? So the energy is going to be, well, what do we do? We put moles of nitrogen dioxide, we want to get rid of that, right? So we go two moles and a two like that for every 26 per mole. In fact, we get rid of that because we're using the moles there, okay? When we divide, divide, we cancel, okay? So cancel there, right? So the amount given off. So what do we do? We take 274 divided by 2 and multiply that by negative 114.6. And to three significant figures, you get negative 1.57 times 10 to the 1, 2, 3, 4 kilojoules. Does that make sense? Yes. Okay, so that's how you do it, okay? So next time you have a problem like this, you should be able to do it, okay? Can I kill it? Yes. Any questions? No. Okay, I wonder.