An uncatalyzed elementary reaction has the following energy profile parameters:
• Reactants: 60 kJ mol−1
• Transition state: 140 kJ mol−1
• Products: 25 kJ mol−1
A suitable catalyst is discovered that lowers the potential energy of the transition state by 35 kJ mol−1 but does not alter the energies of reactants or products.
Respond to the prompts below.
(a) Calculate the activation energy of the catalyzed reaction.
(b) Determine the factor by which the activation energy has changed, expressed as a percentage decrease from the uncatalyzed value.
(c) Using collision theory or the Arrhenius relationship in qualitative terms (no calculations required), explain how the catalytic change in part (a) would affect the rate constant at a fixed temperature.
(d) State whether the overall energy change ΔE for the reaction is altered by the catalyst, and justify your answer with reference to the energy profile.