Termolecular Reactions and Pressure Dependence of Rate Constants

Termolecular Reactions and Pressure Dependence of Rate Constants 

Termolecular elementary reactions, whose rates depend on the total pressure, are important in the atmosphere. Examples include the formation of 03, 

The expressions for half-lives and lifetimes in Table 5.2 can be readily derived from the rate laws. For a first-order reaction of a pollutant species A, the rate law for the reaction 

Integrating from time t = 0 when the initial concentration of A is [A]() to time t when the concentration is [A], one obtains 

For second- and third-order reactions, if one assumes the concentrations of the reactants other than A are constant with time, the derivation is the same except that k is replaced by /c[B] (second order) or MB][C] (third order). 

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