Le Chatelier’s principle
Le Chatelier's principle is a fundamental concept in chemistry that states if an external force disrupts the equilibrium of a chemical system, the system will adjust to counteract the change and establish a new equilibrium. Proposed by French chemist Henri Louis Le Chatelier in 1885, this principle remains a cornerstone of chemical understanding today. It applies to various forms of stress, such as changes in temperature, pressure, or concentration of reactants, demonstrating that chemical systems are dynamic and responsive. For example, in an endothermic reaction involving nitrogen dioxide and dinitrogen tetroxide, an increase in temperature will shift the equilibrium to favor the production of nitrogen dioxide, showcasing the principle in action. Beyond chemistry, Le Chatelier's principle has found applications in other fields, including economics, where it helps explain how economic systems adapt to changes and disturbances. This broad relevance highlights the enduring impact of Le Chatelier's work, which continues to inform both scientific inquiry and practical applications.
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Le Chatelier’s principle
Le Chatelier's principle is a law of chemistry stating that if a force disturbs the equilibrium—or the balanced standing—of a substance's chemical makeup, the substance will adapt to the changing factor so that a new equilibrium is achieved. This principle was first proposed in 1885 by French chemist Henri Louis Le Chatelier. Le Chatelier's principle remains a standard fixture in chemistry to the present day.
Overview
Henri Louis Le Chatelier was born in 1850 in Paris, France. He spent some time in military school before studying at the Collège Rollin, École Polytechnique, and École des Mines. He served in the Franco-Prussian War and later worked as a mining engineer before embarking on a career in chemistry.
In 1884, Le Chatelier made the discovery for which he would become most famous. By that year, Le Chatelier had become a chemistry professor at École des Mines, where he continued his scientific pursuits by examining the laws, properties, and other facets of chemistry. As a chemist, he studied a range of fields, from metallurgy to glass, fuels, and explosives. But it was while he was studying the chemical makeup of cement that Le Chatelier first defined Le Chatelier's principle, his most notable contribution to the world of science. This chemical law stated that if the balanced chemical forces, or equilibrium, of a substance are disturbed by an outside force, the substance will compensate for the change, if possible, by establishing a new equilibrium. In this way, a substance adapts to altering forces to maintain the necessary chemical balance of all parts of the equation that created it.
In 1885, Le Chatelier made his discovery public when he presented it to the Academie des Sciences in Paris, where his proposal was lauded by his peers. Three years later, Le Chatelier officially published his findings in the scholarly publication Annals of Mines. In his published essay, Le Chatelier defined and elaborated on his principle to prove its constant presence in nature.
Le Chatelier wrote that a force that seeks to change the chemical equilibrium of a substance can be viewed as a stress. This stress can refer to anything from a change in temperature to an increase or decrease in pressure. When a chemical balance is forced to undergo this stress, it compensates for the alteration by rebalancing toward one side of the equation or the other, as Le Chatelier described it.
An example of exactly how this works can be applied to the chemical equation used to define the production of hydrogen gas. The reactants, or initial components, of the equation contain a specific number of carbon atoms and water molecules (composed of hydrogen and oxygen atoms) that, when combined correctly in the proper quantities, yield the desired product, the hydrogen gas. Because the intricate equation is balanced in the correct way, it is at equilibrium.
But a stress, such as a change in temperature or a change the concentration of elements, can alter this equation so that the quantity of reactants is no longer the same. For example, now the set number of water molecules (H2O) in the first part of the equation is different. Because the nature of the reactants has changed, the product must also change to compensate, for the exact quantity or type of hydrogen gas that was initially expected can no longer be produced. Now, instead of a certain amount of hydrogen gas, the equation will yield more hydrogen alongside the compound carbon monoxide. This is an example of the essential ripple effect that one form of stress can have on a chemical substance, which proves the absolute veracity of Le Chatelier's principle.
Le Chatelier died in 1936 in Miribel-les-Échelles, France, but his principle lived on and continued to be used by both chemists and non-chemists alike when it was discovered that it could apply to other fields of study. In the 1940s, American economist Paul Samuelson devised a method of using Le Chatelier's principle to identify shifts in the equilibrium of world economies due to certain stresses. His basic logic in doing so was that if at any point a change should occur in an economic system, the effects of that change would be felt and then adapted to in all related economic sectors. Samuelson won the Nobel Prize in 1970 for his work in this field. In this way, Le Chatelier's principle survived its creator and continued to be a pillar of chemical law and of scientific law in general.
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