Question

The chemical reaction 2O₃ → 3O₂ proceeds as follows: O₃ fast O₂ + O O + O₃ slow 2O₂ The rate law expression should be:

• A. r = k[O₃]
• B. r = k[O₃][O₂]⁻¹
• C. r = k[O₃]²[O₂]²
• D. r = k[O₃][O₂]²

Hint:

Rate law depends on the slow (rate-determining) step.

Answer 1

The Correct Option is A

The slow step is rate-determining: r = k[O][O₃] From the fast equilibrium: O₃ O₂ + O [O] [O₃][O₂] Substituting: r [O₃]²[O₂] Since [O₂] is nearly constant, it is absorbed into k: r = k[O₃]