Because of its importance in atmospheric chemistry, the thermal decomposition of nitric oxide, 2 NO (g) -7 N,(g) + O,(g), has been amongst the most thoroughly studied of gas-phase reactions. The commonly accepted mechanism has been that of H. Wise and M.F. Freech (J. Chem. Phys. 22, 1724 (1952)):

(a) Label the steps of this mechanism as initiation, propagation, etc.
(b) Write down the full expression for the rate of disappearance of NO. What does this expression for the rate become on the basis of the assumptions that v2 = v3 when [N] reaches its steady state concentration, that the rate of the propagation step is more rapid than the rate of the initiation step, and that oxygen atoms are in equilibrium with oxygen molecules?
(c) Find an expression for the effective activation energy, Ea elf' for the overall reaction in terms of the activation energies of the individual steps of the reaction.
(d) Estimate Ea elf from the bond energies of the species involved.
(e) It has been pointed out by R. J, Wu and CT. Yeh (Int. f. Chem. Kinet. 28, 89 (1996)) that the reported experimental values of Ea,elf obtained by different authors have varied from 253 to 357 k] mol-I They suggest that the assumption of oxygen atoms and oxygen molecules being in equilibrium is unwarranted and that the steady-state approximation needs to be applied to the entire mechanism. Obtain the overall rate law based on the steady-state approximation and find the forms that it assumes for low NO conversion (Iow 0, concentration).
(f) When the reaction conversion becomes significant, Wu and Yeh suggest that two additional elementary steps,

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(1) NO+ NO → N,0+0 k2 (2) O+ NO0, +N ks (3) N+NO N, +0 (4) O+0+M+0, +M (5) 0,+M →0+0+M (6) O,+M →0+0+M kg (7) NO+0, →0+ NO,