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Mechanistic Analysis of Solution Reactions by Non‐Isothermal Calorimetry
Author(s) -
Koch Erhard
Publication year - 1973
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.197303811
Subject(s) - thermodynamics , isothermal process , enthalpy , chemistry , activation energy , thermal analysis , order of reaction , differential thermal analysis , kinetic energy , reaction rate constant , standard enthalpy of reaction , reversible reaction , thermal , kinetics , organic chemistry , physics , diffraction , optics , catalysis , quantum mechanics
For the rapid kinetic and energetic analysis of reactions in solution (τ 20°C > 10 ‐4 s) by differential thermal analysis (DTA), the following thermogram parameters are defined as characterizing the start of the reaction: 1. initial temperature, 2. activation energy of the initiation reaction. In conjunction with the shape index (asymmetry of the DTA curve) and the half width of the DTA curve referred to standard physical conditions (cell constant, heating rate, and temperature difference), these quantities allow a simple distinction between one‐step reactions of first and second order and composite reactions. It is possible to recognize whether a process involves parallel, successive, or equilibrium reactions, or combinations of these. The reaction mechanism can be clarified in many cases by measurements at various concentrations and heating rates and by discussion of the enthalpy values. The shortened method described in this report for the evaluation of the thermograms was derived with the aid of an analog computer and checked experimentally.