Which statement best describes how a catalyst can speed up a chemical reaction?

• A. A catalyst increases the equilibrium constant of the reaction.
• B. A catalyst changes the overall enthalpy change of the reaction.
• C. A catalyst provides additional reactants to the reaction mixture.
• D. A catalyst lowers the activation energy required for the reaction to occur.

Answer: (D)

Verified step by step guidance

1. Understand that a catalyst affects the rate of a chemical reaction by providing an alternative reaction pathway with a lower activation energy.
2. Recall that the activation energy is the minimum energy required for reactants to transform into products, and lowering it increases the reaction rate.
3. Recognize that a catalyst does not change the equilibrium constant (\(K\)) because it speeds up both the forward and reverse reactions equally, so the position of equilibrium remains unchanged.
4. Note that a catalyst does not alter the overall enthalpy change (\(\Delta H\)) of the reaction, as enthalpy is a state function dependent only on initial and final states, not the pathway taken.
5. Understand that a catalyst does not add reactants to the mixture; it only facilitates the existing reactants to convert into products more efficiently.