How is Gibbs energy affected by pressure in a condensed phase?

Gibbs energy, which is a thermodynamic potential, reflects the balance between enthalpy and entropy for a system and is influenced by both temperature and pressure. In condensed phases such as liquids and solids, the average molar volume is much smaller than that of gases, resulting in comparatively modest compressibility. As pressure changes, the Gibbs energy does not remain constant but instead varies.

The relationship between Gibbs energy and pressure can be understood through the Gibbs-Helmholtz equation and the Clapeyron equation, which describe how the free energy is affected by both pressure and temperature. Specifically, for condensed phases, the effect of pressure on Gibbs energy is tied to the molar volume — when pressure increases, the molar volume decreases, leading to a change in the Gibbs energy.

As pressure increases, and given that the molar volume (which is nearly constant for solids and liquids) contributes to the change in Gibbs energy, one can deduce that the Gibbs energy will adjust according to the molar volume and the change in pressure. Therefore, it is most accurate to say that Gibbs energy is dependent on molar volume and pressure difference, which aligns perfectly with the concept of how these thermodynamic variables interact within a condensed phase.