Le Chatelier's Principle
This phenomenon is explained by Le Chatelier's Principle, which states:
* If a change of condition is applied to a system in equilibrium, the system will shift in a direction that relieves the stress.
Adding a Product
Adding a product to a system at equilibrium is a stress on the system. To relieve this stress, the equilibrium will shift to the left, favoring the reverse reaction.
Why it Shifts Left
* Increased Product Concentration: By adding more product, you increase its concentration. The system tries to reduce this excess product by converting it back into reactants.
* Re-establishing Equilibrium: The reaction shifts left until a new equilibrium is reached where the product concentration is slightly lower, and the reactant concentration is slightly higher.
Example: The Haber Process
Consider the Haber process for producing ammonia:
N₂(g) + 3H₂(g) ⇌ 2NH₃(g)
* If ammonia (NH₃) is added to the system at equilibrium, the reaction will shift to the left, favoring the formation of nitrogen (N₂) and hydrogen (H₂).
Important Note: The extent of the shift depends on the magnitude of the change in concentration and the equilibrium constant (K) of the reaction.
