Which of the following best describes the effect of activation energy on a chemical reaction?

• A. Activation energy has no effect on the rate of a chemical reaction.
• B. A higher activation energy speeds up the reaction because more molecules can overcome the energy barrier.
• C. A higher activation energy slows down the reaction because fewer molecules have enough energy to react.
• D. A lower activation energy makes the reaction non-spontaneous.

Answer: (C)

Verified step by step guidance

1. Understand that activation energy (E_a) is the minimum energy barrier that reactant molecules must overcome to transform into products during a chemical reaction.
2. Recall that the rate of a chemical reaction depends on how many molecules have enough energy to surpass this activation energy barrier at a given temperature.
3. Recognize that a higher activation energy means fewer molecules have sufficient energy to react, which results in a slower reaction rate.
4. Conversely, a lower activation energy means more molecules can overcome the barrier, leading to a faster reaction rate.
5. Note that activation energy affects the reaction rate but does not determine whether a reaction is spontaneous; spontaneity is related to thermodynamic factors like Gibbs free energy.