What is the role of a catalyst in a chemical reaction?

• A. It is consumed during the reaction and becomes part of the products.
• B. It increases the rate of the reaction by lowering the activation energy.
• C. It increases the equilibrium constant of the reaction.
• D. It changes the enthalpy change (ΔH) of the reaction.

Answer: (B)

Verified step by step guidance

1. Understand that a catalyst is a substance that affects the speed of a chemical reaction without being consumed in the process.
2. Recognize that a catalyst works by providing an alternative reaction pathway with a lower activation energy, which is the minimum energy required for reactants to transform into products.
3. Note that because the catalyst lowers the activation energy, it increases the rate at which the reaction reaches equilibrium, but it does not change the position of the equilibrium itself.
4. Remember that the catalyst does not alter the overall enthalpy change (ΔH) of the reaction, since ΔH depends only on the initial and final states of the system, not on the pathway taken.
5. Conclude that the primary role of a catalyst is to increase the reaction rate by lowering the activation energy, without being consumed or changing the equilibrium constant or enthalpy change.