When an exothermic reaction takes place in a container, heat is released and the temperature of the container and its contents increases. The contents of the container include: the reaction products and typically a solvent (such as water). The measurement of heat transfer under controlled conditions is called calorimetry (from the unit of heat energy, the calorie), and a container used to measure heat transfer is called a calorimeter. The calorimeter prevents heat transfer to or from the surroundings, thereby isolating the system being measured.
When a reaction occurs in a relatively large amount of water, we can relate to the water as the sole medium absorbing the heat of reaction. We can then calculate the heat of reaction by measuring the temperature change of the water, according to the following relationships:
where Cp(water) is the specific heat of water, 4.18 J/g°C, and deltaT is the difference between the initial and final temperatures.
The absorption of heat by the calorimeter should also be taken into account and added to the heat absorbed by the water. The calorimeter constant, Ccal, for the calorimeter you will use is 9.3 J/deg-C. The total heat of the reaction is given by: