What is Le Chatelier's Principle?

Le Chatelier's principle is a simple law of physics related to the scientific study of chemistry and chemical reactions. This principle states that the equilibrium of a chemical solution will balance itself when changes in condition, such as temperature, pressure, volume, and concentration, are introduced. Countering forces will balance these changes, resulting in a new point of equilibrium. Le Chatelier's principle has been applied to other areas of science and physics under many different names. In all incarnations of the principle, it can easily be summed up in layman's terms: Change in a system results in an opposite reaction to achieve balance.

This physical law receives its name from its discoverer, French chemist Henry Louis Le Chatelier. He wrote no less than 30 scientific papers detailing his research and laboratory experiments from 1884 to 1914. These combined works later came to be known as Le Chatelier's principle. His research has proven important to the field of chemistry because it formed a foundation that allows researchers to effectively predict the outcome of changes in a chemical solutions equilibrium.

Using Le Chatelier's principle, chemistry researchers can effectively predict the outcome of their experiments. For example, they can predict that a chemical reaction producing an endothermic action can be altered by introducing a separate exothermic reaction. The ability to predict the reaction and balanced states of chemical solutions is often used to increase the yield of a reaction's product by providing controlled variables. This law is also applied to medical chemistry to create pharmaceutical drugs that block receptors of certain chemicals in the body.

To understand how Le Chatelier's principle works in the field of chemistry, it helps to look at an example from the world of physics. This physical law works on a cause and effect basis. One example would be the surface level of water in a U-shaped tube. With such a tube, an individual can pour water into one side and the water level of the other side will rise until the water level in both sides is equal. At this point, the water has reached equilibrium.

With the water at equilibrium, the levels in both sides of the tube are balanced. If an outside force is exerted on the water in one side of the tube, such as downward pressure of a plunger, the water level on the other side will raise and establish a new point of equilibrium. If the plunger has a hole in it, then the water will gradually leak past the plunger and return to another point of equilibrium.