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In chemistry, Le Châtelier's principle, also called Chatelier's principle or "The Equilibrium Law", can be used to predict the effect of a change in conditions on a chemical equilibrium. The principle is named after Henry Louis Le Châtelier and sometimes Karl Ferdinand Braun who discovered it independently. It can be stated as: :When a system at equilibrium is subjected to change in concentration, temperature, volume, or pressure, then the system readjusts itself to (partially) counteract the effect of the applied change and a new equilibrium is established. or whenever a system in equilibrium is disturbed the system will adjust itself in such a way that the effect of the change will be nullified. (in short) This principle has a variety of names, depending upon the discipline using it (see homeostasis, a term commonly used in biology). It is common to take Le Châtelier's principle to be a more general observation, roughly stated: :''Any change in status quo prompts an opposing reaction in the responding system''. In chemistry, the principle is used to manipulate the outcomes of reversible reactions, often to increase the yield of reactions. In pharmacology, the binding of ligands to the receptor may shift the equilibrium according to Le Châtelier's principle, thereby explaining the diverse phenomena of receptor activation and desensitization.〔(【引用サイトリンク】title=The Biophysical Basis for the Graphical Representations )〕 In economics, the principle has been generalized to help explain the price equilibrium of efficient economic systems. In simultaneous equilibrium systems, phenomena that are in apparent contradiction to Le Châtelier's principle can occur; these can be resolved by the theory of response reactions. ==Status as a Physical Law== Le Châtelier's principle describes the qualitative behavior of systems where there is an externally induced, instantaneous change in one parameter of a system; it states that a behavioural shift occurs in the system so as to oppose (partially cancel) the parameter change. The duration of adjustment depends on the strength of the negative feedback to the initial shock. Where a shock initially induces positive feedback (such as thermal runaway), the new equilibrium can be far from the old one, and can take a long time to reach. In some dynamic systems, the end-state cannot be determined from the shock. The principle is typically used to describe closed negative-feedback systems, but applies, in general, to thermodynamically closed and isolated systems in nature, since the second law of thermodynamics ensures that the disequilibrium caused by an instantaneous shock must have a finite half-life.〔 ''For full details, see'': 〕 The principle has analogs throughout the entire physical world. The principle while well rooted in chemical equilibrium and extended into economic theory, can also be used in describing mechanical systems in that the system put under stress will respond in a way such as to reduce or minimize that stress. Moreover, the response will generally be via the mechanism that most easily relieves that stress. Shear pins and other such sacrificial devices are design elements that protect systems against stress applied in undesired manners to relieve it so as to prevent more extensive damage to the entire system, a practical engineering application of Le Chatelier's principle. 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「Le Chatelier's principle」の詳細全文を読む スポンサード リンク
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