Students investigate the thermodynamics of physical and chemical changes that absorb and release heat energy with this 2-activity kit. They calculate the heats of solution of 2 salt compounds and determine the heat of combustion of a hydrocarbon. For both activities, students write balanced thermochemical equations for the reactions and classify them as endothermic or exothermic. Kit activities take about 45 min. Value Kit materials equip 4 classes of 30 students working in groups of 3.