Gibbs Free Energy
A thermodynamic potential measuring maximum reversible work obtainable from a system at constant temperature and pressure.
Governing formula
G = H - T S, ΔG = ΔH - T ΔS
SI unit
J
In depth
Spontaneous chemical reactions at constant T and P occur if and only if ΔG < 0. Equilibrium occurs when ΔG = 0.
Examples in the real world
ATP hydrolysis releasing Gibbs free energy (ΔG < 0) to power biological muscle contractions.