A coffee cup calorimeter shows how much heat has been used or lost during a chemical reaction. This is done by measuring the temperature of the water inside the cup while the reaction occurs. The calorimeter is a simple tool for performing experiments safely in a classroom or at home.
A coffee cup calorimeter is basically a Styrofoam cup filled with a chosen volume of water. The cup has a lid with a thermometer stuck through the hole in the top, bulb side down, to measure the temperature of the water. The reaction causes heat to be absorbed into the water. This is used to calculate the heat flow by taking the specific heat of water and multiplying it by the mass of the water, then taking that sum and multiplying it by the change in water temperature.