Determine the heat of combustion of Mg, first three empty Styrofoam cups were weighed with an electronic balance. The results were recorded. Second, a 21 ml of HCl was poured in the Styrofoam cup. This was in order to fully dissolve the Mg. Third, the temperature of the solution was measured (using a thermometer) in a covered Styrofoam cup until it reached the highest temperature. The initial temperature was recorded. After that, the magnesium was added to the covered Styrofoam cup. Finally, the temperatures of solutions were recorded when thermometer reached the highest number.