Le Chatelier's principle

The principle states, that if an equilibrium is disturbed by changing the conditions, the equilibrium moves to the left or right (reactant or product side) to counteract this change. Thus, a new equilibrium is established under different conditions.

Effect of temperature

Exothermic reactions release energy. Therefore, in this case, heat is considered a product. If we add more heat to the system, the equilibrium will shift to the reactant side to counteract the increase in product.

In endothermic reactions, heat is considered a reactant because the reaction consumes energy. Thus, increasing the temperature will shift the equilibrium to the right.

Effect of pressure

If we increase the pressure, the equilibrium will move in order to reduce the pressure again. This is achieved by lowering the number of molecules in the system. Hence, if we increase the pressure, the equilibrium will shift to the side, where the number of molecules is lower.

Effect of concentration

If we increase the concentration of molecules on one side of the reaction equation, the equilibrium will shift to the opposite side. E.g if we increase the concentration of reactant, the equilibrium will shift to the product side.