CHEMISTRY · Multi-part · A Level · Chemistry · Introduction to organic chemistry · Introduction to organic chemistry
Problem
For the gas-phase reaction R → P, an energy profile collected under standard conditions shows two distinct peaks of unequal height separated by a shallow valley.
Assume that the reaction proceeds in two elementary steps with a single reaction intermediate I.
(a) Describe what the unequal peak heights indicate about the relative activation energies of the two steps.
(b) Explain how you could experimentally determine which elementary step is faster using kinetic data, and relate your explanation to the features of the energy profile.
(c) Predict the qualitative effect of adding an inhibitor that raises the energy of I by 15 kJ mol⁻¹ but does not affect either transition state. Discuss how both the reaction rate and the energy profile would be altered.
(d) Would the inhibitor described in part (c) change the overall enthalpy change ΔH_rxn? Justify your answer.