Which statement best describes how increasing temperature affects the rate of a chemical reaction?

• A. The reaction rate increases because more molecules have sufficient energy to overcome the activation energy barrier.
• B. The reaction rate remains unchanged because temperature does not affect molecular collisions.
• C. The reaction rate decreases because the activation energy increases with temperature.
• D. The reaction rate decreases because molecules move more slowly at higher temperatures.

Answer: (A)

Verified step by step guidance

1. Understand that the rate of a chemical reaction depends on how often and how effectively reactant molecules collide.
2. Recall the Arrhenius equation, which relates the reaction rate constant \(k\) to temperature \(T\): \[k = A e^{-\frac{E_a}{RT}}\] where \(E_a\) is the activation energy, \(R\) is the gas constant, and \(A\) is the frequency factor.
3. Recognize that increasing temperature \(T\) increases the exponential term \(e^{-\frac{E_a}{RT}}\), meaning more molecules have enough energy to overcome the activation energy barrier.
4. Conclude that as temperature rises, the number of effective collisions increases, thus increasing the reaction rate.
5. Note that temperature does not increase activation energy nor slow down molecules; instead, it increases their kinetic energy and collision frequency.