What is the term for the amount of heat given off or absorbed in a reaction?

The term that refers to the amount of heat given off or absorbed in a reaction is enthalpy. Enthalpy is a thermodynamic property that reflects the total heat content of a system and is often denoted as "H." When a chemical reaction occurs, the change in enthalpy (ΔH) can indicate whether the reaction is exothermic (releasing heat) or endothermic (absorbing heat). This measurement is crucial in understanding the energy changes that are involved in chemical reactions, which can influence reaction rates and equilibrium.

Other terms, while related to the broader fields of thermodynamics and reaction dynamics, do not specifically describe the heat exchange aspect of reactions. Entropy, for instance, relates to the disorder within a system and is involved in the second law of thermodynamics, which discusses the spontaneity of processes. Kinetics deals with the rate of reaction and the factors that affect how quickly a reaction proceeds, while thermodynamics encompasses the general principles and laws governing energy changes, including but not limited to enthalpy. Hence, enthalpy is the precise term that captures the specific context of heat changes during reactions.