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How do you know to use q = C(deltaT) instead of q = mC(deltaT). Referring specifically to a problem in the textbook, why for number 53 part b do we use C(deltaT)? The question asks: The reaction of 1.40 g of carbon monoxide with excess water vapor to produce carbon dioxide and hydrogen gases in a bomb calorimeter causes the temperature of the calorimeter assembly to rise from 22.113 degrees C to 22.799 degrees C. The calorimeter assembly is known to have a total heat capacity of 3.00 KJ/degree C. Calculate the internal energy change (deltaU) for the reaction fo 1.00 mol CO(g).
You use heat capacity when you don't have a total mass. That is if you know the total mass of the system, you can use the specific heat capacity. In this problem, you are given the heat capacity of the bomb calorimeter and change in temperature. So, you can get q by multiplying them together.
Heat capacity is just heat added divided by the change in temperature. For example, if it takes 30 calories to raise the temperature of a substance 5 degrees Celsius, then the heat capacity is 6 calories per degree Celsius. The specific heat capacity is the heat capacity per unit of mass or moles. If you know that the heat capacity is 6 calories per degree Celsius and that you have 6 grams of the substance, then the specific heat capacity is 1 calorie per gram degree Celsius.
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