The gas-phase reaction is studied at

CHEMISTRY · Single correct · A Level · Chemistry · Rate equations · Rate equations

Problem

The gas-phase reaction

2\,\text{NO}(g) + \text{Cl}_2(g) \to 2\,\text{NOCl}(g)

is studied at

25\,\text{°C}

. The experimentally determined rate law is

\text{rate} = k[\text{NO}]^2[\text{Cl}_2]

. Which of the following proposed mechanisms is most consistent with the observed rate law? (a) Step 1 (slow):

\text{NO} + \text{Cl}_2 \to \text{NOCl} + \text{Cl}

Step 2 (fast):

\text{Cl} + \text{NO} \to \text{NOCl}

(b) Step 1 (fast):

\text{NO} + \text{Cl}_2 \rightleftharpoons \text{NOCl} + \text{Cl}

Step 2 (slow):

\text{Cl} + \text{NO} \to \text{NOCl}

\text{NO} + \text{NO} + \text{Cl}_2 \to 2\,\text{NOCl}

(d) Step 1 (slow):

\text{NO} + \text{NO} \to \text{N}_2\text{O}_2

Step 2 (fast):

\text{N}_2\text{O}_2 + \text{Cl}_2 \to 2\,\text{NOCl}