A further example where disentangling of the kinetic data is necessary

1 A further example where disentangling of the kinetic data is necessary 

Another classic example of a complex reaction is the decomposition of N2O5 which shows first order kinetics, but with the first order rate constant decreasing in value as the pressure is lowered. Superficially, this could be taken as evidence of a typical unimolecular decomposition. However, even a first glance at the stoichiometry of the reaction should suggest that it is unlikely that there is a simple one step breakdown of N2O5 into the products. 

A complex reaction mechanism is likely, and all the experimental facts can be accounted for by the mechanism  

This mechanism has a reversible unimolecular decomposition as a first step. As will be shown later, when unimolecular steps are involved in chain reactions, this can cause a change in order or a change in the value of the rate constant if the pressure is lowered. 

This reaction is important in its own right, but it is also important in showing that all aspects of kinetics must be at one s fingertips when interpreting the kinetic data and proposing a mechanism. To understand the arguments leading to the interpretation of the data for this reaction it is essential that the basics of unimolecular theory, Section 4.5, are understood. It is also essential that, when a predicted rate expression 

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