Le Chatelier's Principle in Chemical Equilibrium
This Demonstration shows how several factors influence the position of a chemical equilibrium: . The three compounds are assumed to separate into visible layers. The parameters include the concentrations of reactants , , and product (colored yellow, purple, and blue, respectively) as well as the pressure , temperature , and volume , all expressed in arbitrary units. The values of these parameters create shifts in the position of the reaction equilibrium, in accordance with Le Chatelier's principle. These are represented by changes in the amounts of the three species, beginning with the initial levels shown in the first cylinder. The pressure and volume cause significant changes only when one or more of the compounds are gases.
Snapshot 1: The pressure and temperature are set to their maximum. High temperature causes more of the product to appear in an endothermic reaction but more of the reactants in an exothermic reaction. Pressure also increases the concentration of the product.
Snapshot 2: The initial concentration of and the volume are maximized. The result is a larger final concentration of and an increase in volume.
Snapshot 3: The initial concentrations of and and the temperature are maximized. An increased concentration of both and causes a smaller final concentration for both. Increased temperature causes more product to appear in an endothermic reaction but more reactants in an exothermic reaction.
 J. C. Kotz, Chemistry and Chemical Reactivity, Pacific Grove, CA: Brooks/Cole, 2005.
 R. E. Davis, Modern Chemistry, Austin, TX: Holt, Rinehart and Winston, 2002.
Special thanks to the mathematics and science departments at William Fremd and Hoffman Estates High School.