An industrial chemist studies the chlorination of compound Z, which proceeds through the two-step mechanism given below.
Step 1: Z → Intermediate J Ea₁ = 110 kJ mol⁻¹ ΔH₁ = +25 kJ mol⁻¹
Step 2: J → Product ZCl Ea₂ = 75 kJ mol⁻¹ ΔH₂ = –95 kJ mol⁻¹
Because Step 1 is slow, a homogeneous catalyst is proposed that selectively lowers the activation energy of Step 1 to 55 kJ mol⁻¹ while leaving all other energetic parameters unchanged.
(a) Calculate the overall enthalpy change, ΔHₒᵥₑᵣₐₗₗ, for the uncatalyzed chlorination of Z.
(b) Draw a quantitatively scaled energy profile for the uncatalyzed reaction, labeling both transition states, the intermediate, and all energy values.
(c) On the same axes, add a second curve that represents the catalyzed pathway. Clearly indicate how the curve differs from the uncatalyzed profile.
(d) Discuss, in two or three well-reasoned sentences, the kinetic and thermodynamic consequences of introducing the catalyst. In your answer, address how the catalyst affects the rate-determining step, the overall rate, and the position of equilibrium.