Thermоchemicаl equаtiоns cаn be written in twо ways; with the heat written on the reactant side (endothermic) or product side (exothermic), or they can be written to the right of the reaction asH with the appropriate sign to indicate positive (endothermic) or negative reaction (exothermic). For the following thermochemical reactions classify them as endothermic or exothermic.