Reduction of NO by H2

In an example discussed earlier we saw that the reaction of NO with H2 leads to a rate expression that is different from what might be expected from the equation of the reaction alone:

The reaction is first order in H2 concentration, not second order. One mechanism that will account for this rate behavior is

This mechanism is illustrated in fig 7 opposite. If all reactions except the k3 process are quite fast, then the rate equation is

You should be able to use the first equilibrium condition to eliminate N202 concentration, and show that the rate equation given previously is the result.