Unopposed reaction

Reaction rates are often compared using a characteristic time. For example, the characteristic time might be defined as the time needed for the destruction of 50% of the reactants (a = p = 0.5). This time is called the reaction s half-life, ty,. When t = ty a= p = 0.5. The half-life for an unopposed reaction where 1 is found by setting m = 0.5 in Eq. (3.18). 

The half-life for an unopposed reaction where k = 1 is found by setting m = O.SinEq. (3.30). 

Both anaphylactoid reactions and bronchospasm have occasionally been reported, although the latter may have been due to sympathetic nervous blockade leading to unopposed parasympathetic effects (SEDA-18,143) (31). 

The above model applies for all values of n other than one. However first-order reactions ( = 1) are relatively common and the integrated form of a first-order unopposed rate equation is much simpler. 

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