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Gibbs free energy




An important function in chemical thermodynamics, defined by

G = H - TS

where H is the enthalpy, S the entropy, and T the thermodynamic temperature. Gibbs free energy is the energy liberated or absorbed in a reversible process at constant pressure and constant temperature. It is sometimes called Gibbs energy and, in older literature, simply "free energy."

Changes in Gibbs free energy, ΔG (= ΔH - TΔS), are useful in indicating the conditions under which a chemical reaction will occur. If ΔG is negative the reaction will proceed spontaneously to equilibrium. In equilibrium position ΔG = 0.


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   • PHYSICAL CHEMISTRY