The rate for the overall reaction:

Question

NO₂(g) + CO(g) ---> NO(g) + CO₂(g) 

is Rate = k[NO₂]²

a) Consider this mechanism:

i) 2 NO₂(g) ---> N₂(g) + 2 O2(g) [slow]

ii) 2 CO(g) + O₂ ---> 2 CO₂(g) [fast]

iii) N₂(g) + O₂(g) ---> 2 NO(g) [fast]

Is this reaction mechanism consistent with the rate law? Why or why not?

b) Write the rate laws for the intermediate steps

c) List the reaction intermediates present in this mechanism

d) Draw a reaction energy diagram for this mechanism, given that the overall reaction's ΔHº_rxn = -226 kJ/mol

Answer 1

a). Yes. Because it contains elements of the slow step, which is a must.

b). i) rate = k[NO₂]

ii) rate = k[CO][O₂]

iii) rate = k[N₂][O₂]

c). O₂ is the reaction intermediate

d). Can't draw on this platform, but you'd start with energy of the reactants HIGHER on the y-axis than the energy of the products (exothermic; negative ∆H) and some finite Ea (energy of activation) as a peak