In LeChatelier’s words, this principle is stated:

Any system in stable chemical equilibrium, subjected to the influence of an external cause which tends to change either its temperature or its condensation (pressure, concentration, number of molecules in unit volume), either as a whole or in some of its parts, can only undergo such internal modifications as would, if produced alone, bring about a change of temperature or of condensation of opposite sign to that resulting from the external cause.

An alternate form of LeChatelier’s Principle is as follows: In chemistry, when a system at equilibrium is changed, the equilibrium will shift to counteract the change.


This investigation will take advantage of your knowledge of LeChatelier’s Principle. It may also deepen understanding of equilibrium in general. The objective is to prepare six equilibrium systems in a set of test tubes that display the colors red, orange, yellow, green, blue, and violet.