A student investigates an elementary decomposition reaction, A₂ → 2A, which has an experimentally determined activation energy of 64 kJ·mol⁻¹. At 300 K, the student measures an initial rate of 4.0 × 10⁻⁴ mol·L⁻¹·s⁻¹.
Without using the Arrhenius equation quantitatively, answer the questions below concerning how the rate will change under different conditions.
(a) When the temperature is increased to 330 K, does the rate of the reaction increase by less than a factor of 2, by about a factor of 2, or by more than a factor of 2? Provide a qualitative justification based on activation energy and collision energy distribution.
(b) At 300 K, a catalyst lowers the activation energy to 48 kJ·mol⁻¹. Estimate whether the catalyzed reaction rate at 300 K is closer to 1 times, 10 times, or 100 times the uncatalyzed rate. Support your estimate with reasoning tied to the shape of the molecular energy distribution.
(c) The student claims that doubling the concentration of A₂ at 300 K will double the reaction rate even after the catalyst is added. Evaluate this claim, explicitly addressing how activation energy and temperature each influence rate compared with concentration changes.