What is the equation for enthalpy?

The equation for enthalpy is defined as H = U + PV, where H represents enthalpy, U is the internal energy of the system, P is the pressure, and V is the volume. This relationship is significant because it accounts for both the internal energy of a system and the energy associated with the pressure-volume work that can be performed by the system.

In thermodynamics, enthalpy is particularly useful in processes occurring at constant pressure, as it simplifies the calculations related to heat transfer. The term PV reflects the work done by the system when it expands or contracts against the external pressure. Therefore, enthalpy incorporates all forms of energy, making it an essential concept for understanding energy changes in chemical and physical processes.

By considering the contributions from both internal energy and pressure-volume work, this equation provides a comprehensive view of how much energy is available to do work during a reaction or phase change under constant pressure, enhancing our understanding of thermodynamic systems.