Chapter 15, Problem 69E

The following mechanism is proposed for the reduction of ${\text{NO}}_3{}^{-}{\text{by MoCl}}_6{}^{2-}:$

$\begin{array}{l}{\text{MoCl}}_6{}^{2-}\underset{k_{-1}}{\overset{k_1}{\rightleftharpoons }}{\text{MoCl}}_5{}^{-}+{\text{Cl}}^{-}\\ {\text{NO}}_3{}^{-}+{\text{MoCl}}_5{}^{-}\stackrel{k_2}{\to }{\text{OMoCl}}_5{}^{-}+{\text{NO}}_2{}^{-}\end{array}$

1. What is the intermediate?
2. Derive an expression for the rate law $\left(\text{Rate}=d\left[{\text{NO}}_2{}^{-}\right]/dt\right)$for the overall reaction using the steady-state approximation.