The reaction 2NO + O2 → 2NO2 is third order. Assuming that a small amount of NO3 exists in rapid reversible equilibrium with NO and O2 and that the rate-determining step is the slow biomelcular reaction NO3 + NO → 2NO2, derive the rate equation for this mechanism

The equation for the rate of this reaction is R = [NO] + {O2}

Explanation:

The rate-determining step of a reaction is the slowest step of a chemical reaction which determines the rate (speed) at which the overall reaction would take place.

Reaction mechanism:

The slow and fast reactions both have NO3 which is cancelled out on both sides, in order to get the overall reaction.

The rate law for this reaction would be that for the rate determining step:

R = [NO] + {O2}