The problem of “inverse reaction kinetics” under the aspect of calorimetric measurements

It is shown that the DTA method performed in a twin stirring-type apparatus has a good chance to successfully meet with the problems of “Inverse Reaction Kinetics”, i.e. to find out an appropriate reaction mechanism including the prevailing activation data of the particular steps for a reacting system studied. Although experimental signal curves can be reproduced using a suitable model and integrating the system of differential equations involved, other ways have to be used for a less tedious approach to the best mechanism.In order to develop adequate diagnostic criteria, the informative potential of different parameters obtained by a simple first/second order evaluation program is studied. For complex processes in solution, the dependencies of such parameters on the initial reactant concentration or on the heating rate often reveal periods of constancy which indicate the rate-determining steps of the mechanism. Based on concentration series of DTA experiments applied to twenty different systems, the following order of increasing kinetic utility of the parameters was found by comparing the number of these occurring periods of constancy:Peak temperature < Overall enthalpy < Initial activation energy < Overall activation energy < Final temperature < Initial A-factor < Relative signal height < Overall A-factor ? Initial temperature < Initial reaction type index < Shape index < Overall reaction type index. By these results, my earlier theoretically founded assumption has been confirmed that the “mechanistic indices” are the best quantities to reveal the reaction mechanism of any reacting system studied.