Chemical reaction that releases more energy than was needed to start it
An exergonic reaction (such as cellular respiration) is a reaction that releases free energy in the process of the reaction. The progress of the reaction is shown by the line. Activation energy (1) slows down the reaction. The change of Gibbs free energy (ΔG) in an exergonic reaction (that takes place at constant pressure and temperature) is negative because energy is lost (2).
In chemical thermodynamics, an exergonic reaction is a chemical reaction where the change in the free energy is negative (there is a net release of free energy).[1] This indicates a spontaneous reaction if the system is closed and initial and final temperatures are the same. For processes that take place in a closed system at constant pressure and temperature, the Gibbs free energy is used, whereas the Helmholtz energy is relevant for processes that take place at constant volume and temperature. Any reaction occurring at constant temperature without input of electrical or photon energy is exergonic, according to the second law of thermodynamics. An example is cellular respiration.
Symbolically, the release of free energy, , in an exergonic reaction (at constant pressure and temperature) is denoted as
Although exergonic reactions are said to occur spontaneously, this does not imply that the reaction will take place at an observable rate. For instance, the disproportionation of hydrogen peroxide releases free energy but is very slow in the absence of a suitable catalyst. It has been suggested that eager would be a more intuitive term in this context.[2]
More generally, the terms exergonic and endergonic relate to the free energy change in any process, not just chemical reactions. By contrast, the terms exothermic and endothermic relate to an enthalpy change in a closed system during a process, usually associated with the exchange of heat.
^IUPAC Gold Book definition: exergonic reaction (exoergic reaction)
^Hamori, Eugene; James E. Muldrey (1984). "Use of the word "eager" instead of "spontaneous" for the description of exergonic reactions". Journal of Chemical Education. 61 (8): 710. Bibcode:1984JChEd..61..710H. doi:10.1021/ed061p710.
and 24 Related for: Exergonic reaction information
In chemical thermodynamics, an exergonicreaction is a chemical reaction where the change in the free energy is negative (there is a net release of free...
release heat. The term is often confused with exergonicreaction, which IUPAC defines as "... a reaction for which the overall standard Gibbs energy change...
exergonicreaction. Another way to phrase this is that useful energy must be absorbed from the surroundings into the workable system for the reaction...
For exergonic and endergonic reactions, see the separate articles: Endergonic reactionExergonicreactionExergonic process Endergonic Exothermic process...
pressure, constant temperature reactions are exergonic if and only if the Gibbs free energy change is negative (∆G < 0). "Exergonic" (from the prefix exo-, derived...
hydrolyzed in a highly exergonicreaction. The energy released by this hydrolysis helps drive the otherwise energetically unfavorable reaction forward. It's the...
products. An endergonic reaction is an anabolic chemical reaction that consumes energy. It is the opposite of an exergonicreaction. It has a positive ΔG...
from bound ADP anion into water solution may be considered as an exergonicreaction because the phosphate anion has low molecular mass. Thus, we arrive...
coupling with an exergonicreaction is necessary.: 25–27 The coupled reaction of the catabolic pathway affects the thermodynamics of the reaction by lowering...
products have a lower Gibbs free energy G = H – TS than the reactants (an exergonic process), even if the enthalpy of the products is higher. Thus, an endothermic...
position. Chemical reactions are determined by the laws of thermodynamics. Reactions can proceed by themselves if they are exergonic, that is if they release...
electrochemical reactions in solutions. In electrogenerated chemiluminescence, electrochemically generated intermediates undergo a highly exergonicreaction to produce...
oxidized pyridine nucleotide (NAD+ or NADP+). This is a reversal of the exergonicreaction of forward electron transfer in the mitochondrial complex I when electrons...
whereas the reaction rates usually become higher with increasing exergonicity of the reaction, electron transfer should, according to Marcus theory, become...
one ion of pyrophosphate to two phosphate ions. This is a highly exergonicreaction, and therefore can be coupled to unfavorable biochemical transformations...
concepts of exothermic and endothermic reactions are generalized to exergonicreactions and endergonic reactions. Thermochemistry rests on two generalizations...
and a suitable dye (sensitizer, or fluorophor). This creates an exergonicreaction. The chemicals inside the plastic tube are a mixture of the dye, the...
{\displaystyle {\ce {B}}} , thus giving a more stable product. The reaction in that case is exergonic and spontaneous. In the first case, when A {\displaystyle...
AlI 3, formed by the reaction of aluminium and iodine or the action of HI on Al metal. The hexahydrate is obtained from a reaction between metallic aluminum...
temperatures, the forward reaction becomes endergonic, favoring the (exergonic) reverse reaction toward CO, even though the forward reaction is still exothermic...
Exergonicreactions are energy-releasing reactions and are generally catabolic. Endergonic reactions require energy and include anabolic reactions and...
9 kJ/mol + 127.6 kJ/mol = −262.3 kJ/mol (exergonic) ΣΔGf = −262.3 kJ/mol + 47.2 kJ/mol = −215.1 kJ/mol (exergonic, but again this does not take into consideration...
Global Information
