In an exothermic reaction at equilibrium, what is the effect of increasing temperature on the position of the equilibrium?

• A. Shifts toward the products (right)
• B. No change in the position of equilibrium
• C. The equilibrium constant changes
• D. Shifts toward the reactants (left)

Answer: (D)

Le Chatelier’s principle says a system at equilibrium will adjust to counteract a disturbance. For an exothermic reaction, heat behaves like a product. If you raise the temperature, you’re adding heat to the system, so the equilibrium shifts in the direction that absorbs heat—the reverse (endothermic) direction. That means more reactants are formed and fewer products, so the position moves to the left. The equilibrium constant does change with temperature (it usually decreases for an exothermic reaction when temperature rises), which aligns with this shift, but the key point here is the leftward move of the equilibrium position.