DECOMPOSITION OF AZOMETHANE

Review

Overall Reaction	AZO → C2H6 + N2
Experimental Rate Law (at low [AZO])	+d[N2]/dt = ka[AZO]2
Proposed Mechanism
Overall Rate of Production of (Azomethane)*	d[AZO*]/dt = + k1[AZO]2 - k-1[AZO][AZO*] - k2[AZO*]
Overall Rate of Production of Nitrogen	d[N2]/dt = k2[AZO*]
Steady State Approximation	d[AZO*]/dt = 0
From the Steady State Approximation	[AZO*]SS = k1[AZO]2 / (k-1[AZO] + k2)
Simplifying Assumption	k-1[AZO] << k2 (low [AZO] case)
Overall (Simplified) Rate of Production of Nitrogen	d[N2]/dt = k1[AZO]2

Summary

Experimental Rate Law (at low [AZO])	+d[N2]/dt = ka[AZO]2
Rate Expression derived from Proposed Mechanism	+d[N2]/dt = k1[AZO]2

Conclusion: The proposed mechanism is consistent with the experimental rate law, provided k_a = k₁

Note: The consistency of the proposed mechanism could be further confirmed by attempting to detect the presence of AZO* during the reaction.