The variation and heat content of the material which react gives the enthalpy (H) the exact name of the heat content. Typically, this variation in heat content or enthalpy is indicated by a change in temperature. There is a change in the temperature of the reaction, during the reaction. The enthalpy change of reaction is represented by ΔH (sometimes called the reaction temperature). The enthalpy of product is H2 and is less than the heat content of H1 reactants.