 So, let's do one of these bomb calorimeter problems. It says a 0.468 gram sample of pentane, and it gets you the molecular formula of pentane C5H12, was burned in a bomb calorimeter. The temperature of the calorimeter and 1.00 kilograms of water in it rose from 20.45 degrees Celsius to 23.65 degrees Celsius. The heat capacity of the calorimeter by itself is 2.21 kilojoules per degree Celsius, and the specific heat capacity of water is 4.184 joules per gram degree Celsius. What is the heat of combustion per mole of pentane? It's not asking for what the heat of combustion of the reaction that you did is per mole of pentane. So, it gives you the mass of the pentane, so you're going to have to convert that to moles. So, watch out about that. So, I guess the thing that we want to do, I guess, is write down the information that the problem gives us. So, it says that the mass of pentane, 0.468 grams, it says that the mass of water is 1. So, it gives us the temperature initial, is 20.45 degrees Celsius, because this is the temperature final, 23.65 degrees Celsius. So, we can calculate Tf, or change in T, which is Tf minus Ti. So, 23.65 degrees Celsius, 20.45. The heat capacity of the calorimeter, it gives you 2. So, C cal is 2.21 kilojoules per mole, or I'm sorry, per degree Celsius. And of course, the specific heat of water is 4.14 joules per gram. Okay, so, how do you do this problem? So, the way to do this problem, first you've got to figure out what is the heat that got from your particular reaction. So, the Q total equals the Q of the water plus the Q of the calorimeter, because that's the whole system. So, we'll move this over here. So, remember, mc delta T. So, m, in this case, remember that's the 3. So, if you want to, you can say 10 to the 3, mc 41184 joules per 1 gram, and delta T, 3.20, I like to put brackets. In this case, notice there's no mass unit for your calorimeter. So, it's just that's the heat capacity. So, 2.21 kilojoules per 1 degree C times of the same delta T, 3.20. Okay, is everybody okay with that formula? What equation is that? So, this is the equation for the bomb calorimeter. So, Q total equals Q H 2 O plus Q cal. That's the equation. So, let's go ahead and cancel out our unit. So, hopefully you guys can see that here we're getting joules, here we're getting kilojoules. And in this problem, I forgot to mention to you guys, it's asking for megajoules per mole. So, let's just go ahead and calculate this first. So, I'm just going to keep this as 3, 9. So, I took this and divided this by 1,000 to get kilojoules. And then I'm going to add that to 2.21 because it's 7. something. 20.4 sales kilojoules. Does everybody get to hear? This is the Q total for this reaction. Okay, but that is this, I mean if this were the answer then this would be one mole. But we don't know if this is one mole because we haven't calculated the number of moles of this. So, let's figure out the number of moles. So, how do we do that? We have to figure out the molar mass of this stuff. So, 12.01 times 1 plus 12 times 1.0 into 2.146 grams per mole. So, let's figure out the number of moles that we have. So, this is the side calculation over here. Number of moles of pimping. So, that's how many moles of pimping you have. So, if we're looking for the heat of combustion per mole. This is the heat of combustion per this many moles. So, we want to know the heat of combustion per mole. All we've got to do is take that number and divide it by this number. 6.49 times 10 to the negative 3 moles. And that will give us kilojoules per mole. Everybody okay with that? So, when we do that, I'm just taking this out to a bunch of 6.6 right now. A lot of kilojoules per one mole. And remember I wanted to do megajoules per mole. So, 1,000 kilojoules per one megajoule. And we do that 8.15. Now, remember the stuff you know already. You just got to put it next to each other. Step by step by step. Any questions on that one? Remember, it's all about canceling units. Why didn't you put the mass of the intake into that first? When you do the Q of H, U plus the Q of K? Because it doesn't matter. Because there's a bomb calorimeter. It's not like the coffee calorimeter. It's just you're measuring the heat that's given off by the sample that's absorbed by the calorimeter and the water itself. So, this is effectively a different type of problem than those coffee cup calorimeter problems. So, remember it'll say bomb calorimeter to allow you. Any questions? That was a good one.