Equilibrium

Definition

Equilibrium in chemistry occurs when the rates of the forward and reverse reactions are equal, resulting in no net change in the concentration of reactants and products. This state can be reached in both closed systems and dynamic processes.

5 Must Know Facts For Your Next Test

1. At equilibrium, the concentrations of reactants and products remain constant over time.
2. The equilibrium constant ($K_{eq}$) expresses the ratio of product concentrations to reactant concentrations at equilibrium.
3. Le Chatelier's Principle states that if a system at equilibrium is disturbed, it will shift to counteract the disturbance and re-establish equilibrium.
4. A large $K_{eq}$ value indicates that products are favored at equilibrium, whereas a small $K_{eq}$ value indicates that reactants are favored.
5. Changes in temperature can affect the position of the equilibrium by changing the value of $K_{eq}$.

Review Questions

• What does it mean for a chemical reaction to be at equilibrium?
• How does Le Chatelier's Principle predict the shift in equilibrium when a system is disturbed?
• What information does the equilibrium constant ($K_{eq}$) provide about a reaction?

Related terms

$K_{eq}$: The equilibrium constant, a number that expresses the ratio of product concentrations to reactant concentrations at equilibrium for a given reaction.

Le Chatelier's Principle:

A principle stating that if an external change is applied to a system at equilibrium, the system adjusts in such a way as to counteract that change and restore a new equilibrium.

Dynamic Equilibrium:

A state where forward and reverse reactions occur at equal rates so that there is no net change in concentration of reactants and products.