What effect does a catalyst have on energy barrier?

• A. It raises the energy barrier
• B. It lowers the energy barrier
• C. It eliminates the energy barrier entirely
• D. It has no effect on the energy barrier

Answer: (B)

A catalyst changes how the reaction proceeds by providing a different path that requires less energy to reach the transition state. That lower activation energy means the rate constant increases, so the reaction goes faster. It doesn’t change the overall energy difference between reactants and products, so the equilibrium composition remains the same. It also doesn’t eliminate the barrier entirely; there’s still a barrier to cross, just a smaller one. And it must affect the rate—it wouldn’t be a catalyst otherwise.