When 0.187 g of benzene, C6H6, is burned in a bomb calorimeter the temperature rises by 3.45 °C. If the heat capacity of the calorimeter is 2.46 kJ>°C, calculate the combustion energy 1∆E2 for benzene in units of kJ/g and kJ/mol.

Video transcript

Hi everyone this problem reads a 0.236 g sample of hexane is combusted in a bomb cal or emitter causing the temperature to rise by 5.59 degrees Celsius, calculate the heat of combustion of hexane and killing joules per mole, given that the calorie meter constant is 2.4 kg joules per degree Celsius. So our goal here is to calculate the heat of combustion of hexane and kill a jules per mole. So the equation that we're going to need to reference for this problem is the heat of our reaction is going to equal negative heat of the calorie emitter where this also equals negative calorie meter constant. Times change in temperature. So the two things that we know here are the calorie meter constant and the change in temperature. So let's go ahead and plug in those values so that we can calculate the heat of our reaction. Okay, so the calorie meter constant. Yes, 2.4 kg jewels per degree Celsius. So let's go ahead and write that in. So 2.4 kg joules per degrees Celsius. And this is multiplied by the change in temperature. So we're told in the problem causing the temperature to rise by 5.59°C. So our change in temperature is 5.59°C. Okay, so the heat of our reaction. Once we do this calculation is equal to negative 11. killed jules. So now we know one part out of two that we need to solve this problem because we're calculating the heat of combustion of hexane. And so our change and internal energy for the combustion of this reaction is going to be in kila jewels over. That's what we're asked to solve. So we just solved for the killer jewels part. So we know that the numerator is negative 11.4036 kg rules. So now we need to figure out the moles of hexane. Okay, so to figure out the moles of hexane, we're going to start off with the grams of hexane were given. So we're told that the sample is 2.36 g of hexane. So our goal here is to go from moles of hexane. Or excuse me, our goal is to go from grams of hexane, two moles of hexane. And we can use that. Or we can find that using the molar mass of hexane. Okay, so we know or will calculate that in one mole of hexane, there is 86.18 g of hex scene. So grams of hexane cancel and we're left with moles of hexane. So once we do this calculation, .236 divided by 86.18. This gives 0. moles of hexane. So now we can go ahead and plug that value into our denominator 0.002738. So let's go ahead and do this calculation. And when we do it, we get negative 4164. kg jewels per mole. And this is going to be our final answer for the heat of combustion of hexane and killing joules per mole. So let's just go ahead and highlight that. So our heat of combustion Is going to equal negative 4164.25. Kill a jules Permal. That is it for this problem. I hope this was helpful.