# Does pressure affect Gibbs free energy?

##### 1 Answer

Sep 9, 2017

Absolutely. It is particularly significant for gases.

The Gibbs' free energy is a function of temperature and pressure. Its Maxwell Relation shows:

#dG = -SdT + VdP#

The

**At constant temperature and pressure, the Gibbs' free energy for systems closed to mass and energy transfer goes to zero.**

This is exemplified in ordinary spontaneous phase transitions, where one has constant temperature and is letting the phase transition occur naturally at a constant atmospheric pressure. Thus,

#DeltaG_"tr" = 0 = DeltaH_"tr" - T_"tr"DeltaS_"tr"#

and at a given phase transition of this sort,

#DeltaS_"tr" = (DeltaH_"tr")/T_"tr"#