Once a system is at equilibrium it’ll stay at equilibrium unless stress is applied in which case the reaction rates will no longer be equal. The system will attempt to re-establish equilibrium at which point forward and reverse reactions will be the same.
Le Chatelier’s Principle allows us to predict how the system will respond in order to re-establish equilibrium after stress has been applied.
TLDR: When a stress is applied to a system at equilibrium, the system will respond to relieve/undo the stress.
Left or Right
Stresses that cause a system at equilibrium to shift:
Right:
- Adding Reactants
- Removing products
Left:
- Adding Products
- Removing Reactants
3 ways to change pressure
- Adding or removing a gaseous reactant or product
- Add an inert gas (a gas not involved in the reaction)
- Change the volume of the container
Catalyst
Adding a catalyst
- Does not change K
- Does not shift position of an equilibrium system
- system will establish equilibrium faster
Catalyst only lowers activation energy for both forward and reverse reactions