When a system at dynamic equilibrium is perturbed, the system will adjust itself to minimize the effects of the perturbation.

• A. Phase Boundaries
• B. Le Chatelier's Principle
• C. Triple Point
• D. Critical Point

Answer: (B)

Le Chatelier's principle explains how a system in dynamic equilibrium responds when disturbed. When you perturb the system—by changing concentration, pressure, or temperature—the balance shifts in the direction that counteracts the change, moving toward a new equilibrium to minimize the effect of the disturbance. For example, adding more reactant increases its concentration, so the system shifts toward products to consume the added reactant. If you remove product, the equilibrium also shifts toward the product side to replenish it. Increasing pressure pushes the system toward the side with fewer moles of gas, while decreasing pressure favors the side with more moles of gas. Temperature changes depend on whether the reaction is endothermic or exothermic: raising temperature favors the endothermic direction, while lowering temperature favors the exothermic direction. Terms that describe phase behavior on a diagram, such as phase boundaries, the triple point, or the critical point, don’t directly describe how a system at equilibrium counteracts a perturbation, so they don’t capture this dynamic response as clearly.