What does Gibbs energy (G) reach at equilibrium?

At equilibrium, the Gibbs energy (G) reaches a minimum value. This concept is a fundamental aspect of thermodynamics, particularly in the context of chemical reactions and phase changes.

When a system reaches equilibrium, the free energy of the system is at its lowest possible level for the given conditions (temperature, pressure, and composition). This is because systems naturally evolve towards states that minimize their free energy. If the Gibbs energy were to increase or decrease from this point, it would indicate that the system has the potential to do work or undergo a change, which contradicts the definition of equilibrium.

The importance of this minimum value of Gibbs energy can also be understood in relation to spontaneity; reactions and processes that occur spontaneously tend to decrease the Gibbs energy of the system, leading it toward that minimum state. At equilibrium, there is no net change in the system, indicating that it has reached a stable configuration that cannot proceed in any direction without external influence.

In contrast, the idea of a maximum value or constant value does not apply in this context, as maximum Gibbs energy states tend to be unstable and not characteristic of equilibrium. Additionally, while pressure does influence Gibbs energy through changes in the stored potential energy, it does not lead to a variable value of Gibbs