A Level Chemistry OCR Practice Exam

According to Le Chatelier's principle, what happens when a system at equilibrium is subjected to a change?

1. The system always favors the formation of products

2. The system will shift to minimize the change

3. The system becomes unstable and cannot maintain equilibrium

4. The system will spontaneously return to its initial state

The correct answer is: The system will shift to minimize the change

The correct answer illustrates the concept of Le Chatelier's principle effectively, stating that when a system at equilibrium experiences a change in concentration, temperature, or pressure, the system will adjust to counteract that change and restore a new equilibrium. This principle highlights that systems tend to self-regulate and maintain equilibrium by shifting the position of equilibrium either to the right (favoring products) or to the left (favoring reactants) based on the nature of the change imposed on the system. For instance, if the concentration of reactants is increased, the system reacts by consuming some of those reactants to form more products, thus shifting the equilibrium position to the right. Conversely, if the temperature of an exothermic reaction is increased, the system will favor the endothermic direction (shifting to the left) to absorb the added heat. Other options do not accurately reflect the behavior of equilibria. The assertion that the system always favors the formation of products oversimplifies interactions since the direction of the shift depends on the specific changes made to the equilibrium conditions. The notion that the system becomes unstable and cannot maintain equilibrium contradicts the essence of Le Chatelier's principle, which asserts that equilibrium can still be maintained even after a disturbance. Lastly,