Further problems on steady states and the Rice-Herzfeld mechanism

6 Further problems on steady states and the Rice-Herzfeld mechanism 

This section ends with two problems, which between them cover a lot of the aspects of chain reactions and use of one of the Rice-Herzfeld rules. The second problem explains how it is that many chain reactions have observed overall activation energies which are considerably less than the bond dissociation energy involved in the first step of the sequence. 

Under certain conditions the reaction appears to have 3/2 order kinetics. Use the Rice-Herzfeld rules to identify the dominant termination step. 

Using the mechanism which has this as the only termination step, verify that it does lead to 3/2 order kinetics. 

Identify the unimolecular steps in this mechanism and indicate what conditions would lead to a requirement for a third body for these steps. 

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