Simultaneous pH-rate profiles applied to the two step consecutive sequenceA -> B -> C: a theoretical analysis and experimental verification

The absorbance extremum method introduced to resolve the rate constant-reac tion step ambiguity problem in two step consecutive reactions is applied to cases where the rate constant in each step is pseudo first order and depen dent on catalyst concentration. In particular, acid and base catalyzed reac tions of substrates in aqueous solution are examined. Resultant simultaneou s pH-rate profile functions are treated in the context of the ambiguity pro blem and a detailed account of the possible interactions between pH-rate pr ofiles is also given. The merits of this method include its general scope, its applicability to reactions for which it may be experimentally difficult to resolve the ambiguity assignment by other means, and its use of rate da ta acquired from original kinetic traces without requiring additional infor mation. The theoretical analysis is verified and tested experimentally for the hydration of fluorenylideneketene in dilute aqueous perchloric acid sol utions.