7.10 Reaction Quotient and Le Châtelier’s Principle

Explain the relationships between Q, K, and the direction in which a reversible reaction will proceed to reach equilibrium.

• A disturbance to a system at equilibrium causes Q to differ from K, thereby taking the system out of equilibrium. The system responds by bringing Q back into agreement with K, thereby establishing a new equilibrium state.
• Some stresses, such as changes in concentration, cause a change in Q only. A change in temperature causes a change in K. In either case, the concentrations or partial pressures of species redistribute to bring Q and K back into equality.