For the reaction the measured rate law is

CHEMISTRY · Subjective · A Level · Chemistry · Rate equations · Rate equations

Problem

For the reaction

2\,\text{NO}_{2}(g) + \text{F}_{2}(g) \to 2\,\text{NO}_{2}\text{F}(g)

the measured rate law is

\text{rate} = k[\text{NO}_{2}]^2

. A chemist proposes the mechanism (1)

\text{NO}_{2} + \text{F}_{2} \rightleftharpoons \text{NO}_{2}\text{F} + \text{F}

(fast, reversible) (2)

\text{NO}_{2} + \text{F} \to \text{NO}_{2}\text{F}

(slow) Explain why

\text{F}_{2}

, although a reactant in the overall balanced equation, does not appear in the rate law.