Question

Write the overall equation for the reaction described by the mechanism above?

Consider the following mechanism:
(A) 2 NO2(g) → N2O4(g)

(B) N2O4(g) + CO → NO(g) + CO2(g)+NO2(g)

Answer 1

Here's my reasoning.

Explanation:

A. Overall equation

`stackrelcolor(blue)(1)(color(red)(cancel(color(black)(2))))"NO"_2"(g)" → color(red)(cancel(color(black)("N"_2"O"_4"(g)")))`
`color(red)(cancel(color(black)("N"_2"O"_4"(g)"))) + "CO(g)" → "NO(g)" + "CO"_2"(g)" + color(red)(cancel(color(black)("NO"_2"(g)")))`
`stackrel(——————————————————)("NO"_2"(g)" + "CO(g)" → "NO(g)" + "CO"_2"(g)")`

B. Identify all intermediates

An intermediate is a species that is formed from the reactants and reacts further to give the products of a chemical reaction.

In other words, it is neither a reactant or nor product. It occurs only in the middle of a reaction mechanism.

Hence, `"N"_2"O"_4"(g)"` is an intermediate in this mechanism.

C. Write the rate law

Each step in a mechanism is an elementary reaction, and a reaction can go no faster than its slowest step.

Hence, for Step (A), the rate law is

`"rate" = k["NO"_2]^2`

D. Order of reaction

The order of the reaction is the sum of the exponents in the rate law.

The reaction is second order.