The variation of Gibbs energy with pressure

If at a certain temperature and pressure the solid phase of a substance has a lower molar Gibbs energy than its liquid phase, then the solid phase is thermodynamically more stable and the liquid will (or at least has a tendency to) freeze. If the opposite is true, the liquid phase is thermodynamically more stable and the solid will melt. For example, at 1 atm, ice has a lower molar Gibbs energy than hquid water when the temperature is below 0°C, and under these conditions water converts spontaneously to ice. 

To discuss how phase transitions depend on the pressure and to iay the foundation for understanding the behavior of soiutions of bioiogicai macromoiecuies, we need to know how the moiar Gibbs energy varies with pressure. 

We show in the foUowing Justification that when the temperature is held constant and the pressure is changed from p, to pf, the molar Gibbs energy of an incompressible liquid becomes 

Variation of the Gibbs energy with pressure (for an incompressible liquid). 

Justification 3.1 The variation ofG of an incompressibie Hquid with pressure 

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The variation of Gibbs energy with pressure The variation of Gibbs energy with temperature... 

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