Reactions A and B occur at with activation energies of and
CHEMISTRY · Single correct · A Level · Chemistry · Kinetics · Kinetics
Problem
Reactions A and B occur at 298K with activation energies of 20kJmol−1 and 80kJmol−1, respectively. The temperature is then raised to 308K. Which reaction will experience the greater percentage increase in its rate, and why?
(a) Reaction A, because a lower activation energy causes the rate constant to be more temperature-dependent, giving it the larger percentage increase.
(b) Both reactions will experience approximately the same percentage increase since the temperature change is identical for both.
(c) Reaction B, because a small temperature rise produces a proportionally larger increase in the fraction of molecules able to surmount a higher activation energy barrier.
(d) Reaction A, because although Reaction B starts slower, Reaction A’s rate is already higher and therefore rises by a larger percentage when the temperature is increased.