|
In chemical thermodynamics, an endergonic reaction (also called a nonspontaneous reaction or an unfavorable reaction) is a chemical reaction in which the standard change in free energy is positive, and energy is absorbed. In layman's terms, the total amount of energy is a loss (it takes more energy to start the reaction than what you get out of it) so the total energy is a negative net result. For an overall gain in the net result see exergonic reaction. Under constant temperature and constant pressure conditions, this means that the change in the standard Gibbs free energy would be positive : for the reaction at standard state (i.e. at standard pressure (1 bar), and standard concentrations (1 molar) of all the reagents). == Equilibrium constant == The equilibrium constant for the reaction is related to Δ''G''° by the relation: : where ''T'' is the absolute temperature and ''R'' is the gas constant. A positive value of Δ''G''° therefore implies : so that starting from molar stoichiometric quantities such a reaction would move backwards toward equilibrium, not forwards. Nevertheless, endergonic reactions are quite common in nature, especially in biochemistry and physiology. Examples of endergonic reactions in cells include protein synthesis, and the Na+/K+ pump which drives nerve conduction and muscle contraction. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「endergonic reaction」の詳細全文を読む スポンサード リンク
|