Le Châtelier's principle allows us to predict what happens to a reaction that is at equilibrium if a change is made. This change might be a change in temperature, pressure or the volume of the container or it might involve adding more reactant or product. Le Châtelier's principle allows us to optimize reaction conditions to obtain the maximum amount of product or to minimize the amount of a product, depending on what we want to do.
Le Châtelier's principle
If an outside influence upsets an equilibrium, the system undergoes a change in a direction that counteracts the disturbing influence and, if possible, returns the system to equilibrium.
Starting from a reaction that is at equilibrium, the following changes could be made: