In this example problem, we'll examine the Constant Volume Calorimeter II in a bomb calorimeter. Our problem reads: "The combustion of liquid hexane has a change in internal energy for the reaction of -3.80 × 10^3 kilograms of hexane reacts in a bomb calorimeter. The temperature rises from 21.9 degrees Celsius to 43.9 degrees Celsius. Calculate the heat capacity of the bomb calorimeter in kilojoules per degree Celsius." For this problem, we can use the equation: Q_cal = C_cal * ΔT. We also make the assumption that the heat absorbed by the calorimeter was released by the reaction, so Q_cal = -Q_reaction. And finally, because this is a bomb calorimeter at constant volume, our change in internal energy for the reaction is equal to the heat released by the reaction, since no pressure-volume work is done. We can combine these equations and rearrange for the heat capacity of the bomb calorimeter: C_cal = -ΔU_reaction / ΔT. To calculate our ΔU_reaction, we have to take into account that we used 2.5 grams of hexane. The ΔU_reaction given in the problem is in units of kilojoules per mole of hexane. Since we did not use one entire mole, we have to determine what the change in internal energy is for the 2.5 grams of hexane that we did use in our reaction. So, we'll use dimensional analysis to convert 2.5 grams of hexane into moles of hexane using the molar mass, and then from moles of hexane into kilojoules using the change in internal energy in kilojoules per mole of hexane. Based on our 2.5 grams of hexane, we should have released 110 kilojoules of energy. The negative sign indicates that the energy is released to the surroundings from the reaction. The energy that was released from the reaction was absorbed by the calorimeter, and we can plug this -110 kilojoules into our equation above to calculate the heat capacity of the bomb calorimeter. We can also plug in our change in temperature of 43.9 degrees Celsius minus 21.9 degrees Celsius. Completing this calculation, we should get 5.01 kilojoules per degree Celsius. This is the heat capacity of the bomb calorimeter.