StellarCalorimetry
Calorimetry is a method used for measuring the release or gain of heat in a chemical or physical reaction using a device called a calorimeter. The most basic version of a calorimeter is known as a coffee-cup calorimeter, in which a coffee cup filled with water has a lid placed over it. Using a thermometer through the lid, the temperature change of the reaction inside the cup can be measured. The most important aspect of calorimetry is the law of conservation of energy. As energy cannot be created or destroyed, the heat gained in a reaction will be equivalent to the heat lost somewhere else. In the case of coffee-cup calorimetry, the “somewhere else” would be the water surrounding the reaction. If the temperature of the water dropped 4 degrees Celsius, it means that the corresponding amount of joules were gained in the reaction (of course, in real experiments, some energy is lost, but in a theoretical perfect system it wouldn’t be).