[simo_dax]

> Enthalpy is basically the relationship between volume, pressure and temperature

I appreciate the non-technical approach to the subject, but this is false. Enthalpy is an energy, it accounts for both internal energy (heat) and work.

[manuka]

Enthalpy is energy required to create a system. Internal energy required to make up the system (to bring it's internals to given Temperature, pressure ect), but there is additional work needed to position the system in the universe (that is, to free some space for it, like moving (working on) water or air to place the system of volume V in it).