What does enthalpy represent in a thermodynamic system?

Enthalpy represents the total heat content of a thermodynamic system, encompassing both the internal energy of the system and the energy associated with the pressure and volume of the system. It provides a useful measure for understanding energy changes during physical and chemical processes, particularly at constant pressure, where changes in enthalpy correspond directly to the heat exchanged. Enthalpy is important in various applications, including calculating the heat involved in reactions, phase changes, and heating or cooling processes. By focusing on the heat content, enthalpy helps to determine whether a reaction is exothermic (releases heat) or endothermic (absorbs heat), making it a key concept in thermodynamics.