Given reaction 2 NO2 + O2 --> N2O5 + O2. It is believed that a species with the formula NO3 is involved in the mechanism, and the observed rate law for the overall reaction is rate = k[NO2][O3]. Propose a mechanism for this reaction that includes the species NO3 and is N2O5 is consistent with the observed rate law.

The rate equation shows us how many atoms or molecules of a certain chemical is present in the slow step. In the above rate equation, it shows that only 1 NO2 and 1 O3 is involved in the slow step. Therefore, when choosing the answer, you should look answer which have only 1 NO2 molecule and 1 O3 molecule in the slow step.

 

NO₂ + O₃      =>      NO₃ + O₂ (slow)
NO₃ + NO₂      =>   N₂O₅ (fast)