The atmospheric decomposition of ozone proceeds by the two-step mechanism shown below.
Step 1: O₃(g) → O₂(g) + O(g)
Step 2: O(g) + O₃(g) → 2 O₂(g)
Assume each step is elementary and occurs on its own reaction coordinate.
(a) For Step 1, identify the bond that is completely broken and any bonds that are partially formed in the transition state.
(b) For Step 2, identify the bonds broken and formed, commenting on how many new O–O bonds arise in the product.
(c) Sketch a combined reaction energy profile that includes both elementary steps on a single reaction coordinate. Label the energies of reactants, the intermediate, both transition states (TS₁ and TS₂), the activation energies E_{a1} and E_{a2}, and the overall energy change.
(d) Using qualitative bond-energy reasoning, account for any difference you expect between E_{a1} and E_{a2}. Explain how the nature of the bonds being broken or formed in each step influences the relative heights of the two barriers.