A chemist investigates the single-step conversion of gaseous species A to gaseous species B. A verbal description of a reaction energy profile for the process is provided below.
• The reactants (A) are assigned an energy of 0 kJ mol⁻¹.
• The potential energy rises steadily to a transition state whose peak lies at 75 kJ mol⁻¹.
• From the transition state, the potential energy decreases to the products (B), which reside at –40 kJ mol⁻¹.
Assume no other elementary steps are involved.
(a) Calculate the activation energy for the forward reaction.
(b) Determine the enthalpy change, ΔH, for the reaction as written (A → B).
(c) Compute the activation energy for the reverse reaction (B → A).
(d) State whether the reverse reaction is endothermic or exothermic and justify your answer using the numerical values obtained above.