Which of the following best describes the effect of increasing temperature on the rate of a chemical reaction?

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

Answer: (D)

Verified step by step guidance

1. Understand the relationship between temperature and reaction rate by recalling the Arrhenius equation: \(k = A e^{-\frac{E_a}{RT}}\), where \(k\) is the rate constant, \(A\) is the frequency factor, \(E_a\) is the activation energy, \(R\) is the gas constant, and \(T\) is the temperature in Kelvin.
2. Recognize that increasing temperature \(T\) decreases the value of the exponent \(-\frac{E_a}{RT}\), which makes the exponential term larger, thus increasing the rate constant \(k\).
3. Know that a higher rate constant \(k\) means the reaction proceeds faster because more molecules have enough kinetic energy to overcome the activation energy barrier \(E_a\).
4. Understand that temperature does not change the activation energy \(E_a\) itself; it only affects the fraction of molecules with sufficient energy to react.
5. Conclude that increasing temperature increases the reaction rate because it increases the number of effective collisions with enough energy to surpass the activation energy, not because molecules move more slowly or activation energy increases.