In terms of chemical equilibrium, what does Le Chatelier's principle state?

• A. Equilibrium always favors products
• B. A change in concentration shifts equilibrium
• C. Temperature changes do not affect equilibrium
• D. The rate of forward reaction equals the rate of reverse reaction

Answer: (B)

Le Chatelier's principle states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract that change and restore a new equilibrium state. This means that when there is a change in concentration, pressure, or temperature, the equilibrium will shift in a direction that tends to minimize the effect of that change.

For instance, if the concentration of a reactant is increased, the system will shift towards the right (the product side) to use up some of the added reactant. Similarly, if the concentration of a product is increased, the equilibrium will shift towards the left to reduce the concentration of that product.

This principle provides insight into how systems respond to changes, emphasizing the importance of concentration in influencing equilibrium. Other choices either misrepresent the principle, ignore the effects of temperature changes, or merely describe the dynamic nature of equilibrium without addressing the response to disturbances. Understanding this principle is crucial for predicting the behavior of chemical reactions under various conditions.