Question

The rate law for the reaction

${\displaystyle 2H_{2\left(g\right)}+2N{O}_{\left(g\right)}\to N_{2\left(g\right)}+2H_2{O}_{\left(g\right)}}$

is given by rate= ${\displaystyle K\left[H_2\right]{\left[NO\right]}^2}$

The reaction occurs in the following two steps:

a. ${\displaystyle H_{2\left(g\right)}+2N{O}_{\left(g\right)}\to N_2{O}_{\left(g\right)}+H_2{O}_{\left(g\right)}}$

b. ${\displaystyle N_2{O}_{\left(g\right)}+H_{2\left(g\right)}\to N_{2\left(g\right)}+H_2{O}_{\left(g\right)}}$

What is the role of N₂O in the mechanism? What is the molecularity of each of the elementary steps?

Answer 1

a. Role of N₂O: N₂O acts as an intermediate since it is produced in first step and consumed in second step. 

b. The first step is trimolecular/termolecular. The second step is bimolecular.