A cup of water plugged by a brown cork is insulated by a second styrofoam cup. A black rod and a thermometer are inserted through the cork into the water. The thermometer is A, the water is B, the outer cup is C. This part insulates the reaction chamber from the transfer of heat to or from the surrounding environment. This part contains a known amount of water, which is placed there before the experiment starts. This part is where the metal is placed at the beginning of the experiment. This part is used for measuring the initial and final temperatures of the water.