Which of the following best describes the role of a catalyst in the energetics of a chemical reaction?

• A. A catalyst changes the overall enthalpy change (ΔH) of the reaction.
• B. A catalyst lowers the activation energy, increasing the reaction rate without being consumed.
• C. A catalyst increases the activation energy, making the reaction slower.
• D. A catalyst is consumed during the reaction and alters the equilibrium position.

Answer: (B)

Verified step by step guidance

1. Understand that a catalyst affects the energy profile of a chemical reaction by providing an alternative reaction pathway.
2. Recall that the activation energy (E_a) is the minimum energy required for reactants to transform into products.
3. Recognize that a catalyst lowers the activation energy, which increases the rate at which the reaction proceeds.
4. Note that the catalyst does not change the overall enthalpy change (\$\Delta H\$) of the reaction, meaning the energy difference between reactants and products remains the same.
5. Remember that a catalyst is not consumed in the reaction and does not alter the equilibrium position; it only helps the system reach equilibrium faster.