Nitrogen dioxide reacts with carbon monoxide according to the overall equation
NO2(g) + CO(g) → NO(g) + CO2(g).
In the absence of a catalyst the activation energy for the rate-determining step is 125 kJ mol−1. When Pt(s) is introduced as a heterogeneous catalyst, the reaction proceeds by an alternative pathway whose rate-determining step has an activation energy of 55 kJ mol−1. For purposes of comparison, assume that the pre-exponential factor A in the Arrhenius expression is the same for both pathways.
(a) Calculate the ratio kcat/kuncat at 298 K.
(b) Calculate the same ratio at 350 K.
(c) Based on your results, determine which pathway dominates the overall reaction rate at each temperature and justify your answer.