Gibbs free energy
The energy that is either released, or used by, a chemical reaction. The free energy absorbed or released during a reaction (ΔG) is the difference between the energy of the products and the energy of the reactants (ΔG =Gr-Gf) and is given by: ΔG = ΔH–tΔS where: ΔH is the energy released (or used) in chemical bond breakage (or formation) during the chemical reaction. ΔS is a measure of the change in entropy (disorder) of the molecules involved in the reaction. t is the temperature at which the reaction occurs. For a bimolecular reaction, A + B --> C + D ΔG = ΔG°´ + RT ln([C]c[D]d/[A]a[B]b) where ΔG°´ is the standard free energy for the reaction under standard biological conditions. See standard transformed constants.