NCEA Level 3 Chemistry (AS91393) Practice Exam 2026 – Complete Aqueous Chemistry Prep

The position of equilibrium is influenced by several factors, including the concentration of reactants and products, temperature, and pressure for gaseous systems. However, a catalyst does not affect the equilibrium position.

A catalyst speeds up the rate at which equilibrium is reached, but it does not change the concentrations of reactants and products at equilibrium. Therefore, while the time to reach equilibrium is decreased, the relative amounts of reactants and products when equilibrium is established remain unchanged. This fundamental characteristic of catalysts highlights their role in influencing reaction kinetics without altering the chemical equilibria of the system.

In contrast, changes in concentration can shift the position of equilibrium in accordance with Le Chatelier's principle, where the system adjusts to minimize the effect of the change. Changes in temperature can also shift equilibrium positions based on whether the reaction is exothermic or endothermic, while pressure changes affect equilibria involving gaseous reactants or products by shifting the equilibrium toward the side with fewer moles of gas under increased pressure.