Consider the reversible gas-phase reaction A⇌B carried out at 475 K. A potential-energy profile for the uncatalyzed reaction is described verbally as follows.
• Reactants (A): 0 kJ mol⁻¹ (reference)
• Transition state: 165 kJ mol⁻¹
• Products (B): –52 kJ mol⁻¹
A solid catalyst is found to lower the activation energy of both the forward and reverse reactions by exactly 45 kJ mol⁻¹.
(a) Calculate the activation energy for the forward and reverse reactions in the presence of the catalyst.
(b) Determine the enthalpy change ΔH for the reaction and explain whether this quantity is affected by the catalyst.
(c) At 475 K, predict whether the catalyst changes the numerical value of the equilibrium constant K_p. Provide a justification based on kinetic and thermodynamic principles.
(d) If the system starts with pure A and the catalyst is present from the beginning, describe qualitatively how the time required to reach equilibrium will compare with the uncatalyzed case.