Le Châtelier’s principle

Definition

Le Châtelier’s principle states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium moves to counteract the change. This principle helps predict how changes in concentration, temperature, or pressure affect chemical systems at equilibrium.

5 Must Know Facts For Your Next Test

1. Changing the concentration of reactants or products will shift the equilibrium to restore balance.
2. Increasing temperature for an endothermic reaction shifts equilibrium to the right (towards products), while increasing temperature for an exothermic reaction shifts it to the left (towards reactants).
3. Decreasing volume (increasing pressure) favors the side of the reaction with fewer gas molecules.
4. Adding a catalyst does not shift the equilibrium position; it only speeds up the rate at which equilibrium is reached.
5. Le Châtelier’s principle can be used to optimize industrial chemical processes, such as ammonia production in the Haber process.

Review Questions

• How does increasing the concentration of a product affect the position of equilibrium according to Le Châtelier’s principle?
• What effect does decreasing temperature have on an exothermic reaction at equilibrium?
• Why doesn’t adding a catalyst change the position of equilibrium?

Related terms

Dynamic Equilibrium:

A state where the rate of forward reaction equals the rate of backward reaction, resulting in no net change in concentrations of reactants and products.

Endothermic Reaction:

A chemical reaction that absorbs heat from its surroundings.

Exothermic Reaction:

A chemical reaction that releases heat into its surroundings.