## Hmwk 9.91 gibbs in the vaporization of water

$\Delta G^{\circ}= \Delta H^{\circ} - T \Delta S^{\circ}$

$\Delta G^{\circ}= -RT\ln K$

$\Delta G^{\circ}= \sum \Delta G_{f}^{\circ}(products) - \sum \Delta G_{f}^{\circ}(reactants)$

kshalbi
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### Hmwk 9.91 gibbs in the vaporization of water

To find the Gibbs free energy for the vaporization of water at 25 degrees Celsius, why can't you subtract the Gf of the gaseous state of water and the Gf of the liquid state of water?

Chem_Mod
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### Re: Hmwk 9.91 gibbs in the vaporization of water

You can do it this way particularly for 25C, but the book solution just wants to show the same method for all the different temperatures because the free energies of formation are only for 25C.