For the oxidation of nitric oxide, a plausible gas-phase mechanism is proposed:
Step 1 2NO(g) ⇌ N₂O₂(g) (fast)
Step 2 N₂O₂(g) + O₂(g) → 2NO₂(g) (slow)
Derive the rate law for the overall formation of NO₂, expressing the rate solely in terms of the concentrations of NO and O₂ and an observed rate constant kobs.