What is the symbol used to denote enthalpy?

The symbol used to denote enthalpy is H. Enthalpy is a thermodynamic quantity that represents the total heat content of a system and is a function of pressure, volume, and temperature. It is especially useful in chemistry and physics for understanding energy changes during chemical reactions and phase changes at constant pressure.

In thermodynamics, the enthalpy of a system can be expressed mathematically as H = U + PV, where U is the internal energy, P is the pressure, and V is the volume. Since H specifically denotes enthalpy, it is important to distinguish it from other thermodynamic symbols.

The other choices do not represent enthalpy: E generally represents internal energy, S symbolizes entropy, and P denotes pressure. Thus, H is the correct and recognized symbol for enthalpy in the context of thermodynamics.