Le Chatelier’s Principle

• Le Chatelier’s Principle

  • Also known as the Equilibrium law
  • A principle stating that if a stress is applied to a system in equilibrium, the equilibrium shifts to relieve the stress.
• Three ways that changes the shift of equilibrium:

  1. Changing the concentration of the reactants or products.
  2. Changing the pressure or volume of the system.
  3. Changing the temperature of the reaction.
• The presence of a catalyst does not alter the equilibrium constant. Its effect is to decrease the time needed for the system to reach a state of equilibrium.
• Shift to the right (Forward direction)


  Increase concentration of the Reactants

  Decrease concentration of the Products
• Shift to the left (Backward direction)

  • Increase concentration of the Products
  • Decrease concentration of the Reactants
• Shifts to the lesser moles of gas

  • Increase in pressure
  • Decrease in volume
• Shifts to the greater moles of gas

  • Decrease in pressure
  • Increase in volume
• Exothermic Reaction: Shift to the left 


  Increase in temperature
• Exothermic Reaction: Shift to the right


  Decrease in temperature
• Endothermic Reaction: Shift to right 


  Increase in temperature
• Endothermic Reaction: Shift to the left


  Decrease in temperature