Catalysts cannot change the energy difference between reactants and products.

Catalysts cannot change the energy difference between reactants and products.

• A. They always increase energy difference
• B. They can change energy difference
• C. They cannot change the energy difference between reactants and products
• D. They decrease the energy difference

Answer: (C)

Catalysts change how fast a reaction happens, not the energy difference between reactants and products. They provide an alternate pathway with a lower activation energy, so the energy barrier to reach the transition state is smaller, and the reaction proceeds more quickly. But the overall thermodynamics—the final energy level of the products relative to the reactants, i.e., the energy difference ΔG or ΔH—remains the same. The catalyst doesn’t alter the relative stability of reactants and products, it just accelerates both the forward and reverse steps along the same energy landscape. As a result, the equilibrium position (the ratio of products to reactants at a given temperature) stays unchanged, even though the reaction reaches that equilibrium faster.

Catalysts change how fast a reaction happens, not the energy difference between reactants and products. They provide an alternate pathway with a lower activation energy, so the energy barrier to reach the transition state is smaller, and the reaction proceeds more quickly. But the overall thermodynamics—the final energy level of the products relative to the reactants, i.e., the energy difference ΔG or ΔH—remains the same. The catalyst doesn’t alter the relative stability of reactants and products, it just accelerates both the forward and reverse steps along the same energy landscape. As a result, the equilibrium position (the ratio of products to reactants at a given temperature) stays unchanged, even though the reaction reaches that equilibrium faster.