Exergonic reaction
![An exergonic reaction (such as cellular respiration) is a reaction that loses energy during the process of the reaction. Activation energy (1) catalyzes the reaction to occur in a spontaneous manner. The progress of the reaction is shown by the line. The change of Gibbs free energy (ΔG) in an exergonic reaction (that takes place under constant pressure and temperature conditions) is a negative value because energy is lost (2).](/Images/godic/202501/12/Exergonic_Reaction.svg2801.png")
An exergonic reaction is a chemical reaction where the change in the free energy is negative (there is a net release of free energy), indicating a spontaneous reaction. For processes that take place under constant pressure and temperature conditions, the Gibbs free energy is used whereas the Helmholtz energy is used for processes that take place under constant volume and temperature conditions.