What occurs when a catalyst is added to a chemical reaction?

• A. The activation energy of the reaction decreases, increasing the reaction rate.
• B. The reaction enthalpy changes, making the reaction more exothermic.
• C. The catalyst is consumed and becomes part of the final products.
• D. The equilibrium position of the reaction shifts toward the products.

Answer: (A)

Verified step by step guidance

1. Understand the role of a catalyst in a chemical reaction: a catalyst provides an alternative reaction pathway with a lower activation energy.
2. Recall that activation energy (\[E_a\]) is the minimum energy required for reactants to transform into products; lowering \[E_a\] increases the reaction rate.
3. Recognize that a catalyst is not consumed in the reaction; it participates temporarily and is regenerated by the end of the reaction.
4. Know that a catalyst does not change the overall enthalpy change (\[\Delta H\]) of the reaction; the energy difference between reactants and products remains the same.
5. Understand that a catalyst does not shift the equilibrium position; it only helps the system reach equilibrium faster by speeding up both the forward and reverse reactions.