Final answer:
Le Châtelier's Principle predicts that a system at equilibrium will shift to counteract any change in concentration, temperature, or pressure, with the goal of re-establishing equilibrium. Catalysts, in contrast, do not affect equilibrium positions but only speed up the achievement of equilibrium.
Step-by-step explanation:
Le Châtelier's Principle states that when a chemical system at equilibrium experiences a change in conditions such as concentration, temperature, or pressure, the system will respond to alleviate that change. For example, if we increase the concentration of reactants, the equilibrium will shift to produce more products in order to reduce the concentration of the added reactants.
Similarly, a decrease in the concentration of products will shift the equilibrium toward the product side to replenish them. Temperature changes can also affect equilibrium: increasing the temperature of an exothermic reaction will shift the equilibrium towards the reactants, while for an endothermic reaction, an increase in temperature will shift it towards the products. Pressure changes predominantly affect gaseous equilibria, with increases in pressure favoring the direction that produces fewer gas molecules.
Catalysts, however, do not shift the position of equilibrium. They accelerate the rate at which equilibrium is achieved without altering the relative concentrations of reactants and products at equilibrium.
Le Châtelier's Principle essentially serves as a guide to predict the effect of external stresses on a system at equilibrium, allowing it to re-establish a new equilibrium state.