Le Chatelier's Principle

A general law, Le Chatelier's principle, can be used to explain the results of applying any change of condition (stress) on a system in equilibrium. It states that if a stress is placed upon a system in equilibrium, the equilibrium is displaced in the direction which counteracts the effects of the stress. An increase in concentration of a substance favors the reaction which uses up that substance and lowers its concentration. A rise in temperature favors the reaction which absorbs heat and so tends to lower the temperature. These ideas are further developed in Effects of Changing Conditions.