How can you have standard enthalpy of formation of water at 298 K?

Firstly, I want to clarify in advance that im not good at this subject.
Secondly, when i go through my chem book to search for thermodynamic data of water at 298 kelvin. I am able to find the standard enthalpy of formation of water in its gaseous state as well as solid state. How can you have water in gaseous/solid form at 298 kelvin? Water only exists in its liquid form at 298 kelvin


Thanks in advance.




Water vapor at 25 C and 1 atm is a hypothetical ideal gas state. You can get the enthalpy of this state by starting with liquid water at 25 C and 1 atm, then dropping the pressure of the liquid to the equilibrium vapor pressure at 25 C, then adding the heat of vaporization at 25 C; for an ideal gas state, going from water vapor at the equilibrium vapor pressure at 25 C to the hypothetical ideal gas sate of 25 C and 1 atm requires no enthalpy change.


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