| Summary: | The Arrhenius plot (logarithmic plot vs. inverse temperature) is represented by a straight line if the Arrhenius equation holds. A curved Arrhenius plot (mostly concave) is usually described phenomenologically, often using polynomials of <i>T</i> or 1/<i>T</i>. Many modifications of the Arrhenius equation based on different models have also been published, which fit the experimental data better or worse. This paper proposes two solutions for the concave-curved Arrhenius plot. The first is based on consecutive A→B→C reaction with rate constants <i>k</i><sub>1</sub> ≪ <i>k</i><sub>2</sub> at higher temperatures and <i>k</i><sub>1</sub> ≫ <i>k</i><sub>2</sub> (or at least <i>k</i><sub>1</sub> > <i>k</i><sub>2</sub>) at lower temperatures. The second is based on the substitution of the temperature <i>T</i> the by temperature difference <i>T</i> − <i>T</i><sub>0</sub> in the Arrhenius equation, where <i>T</i><sub>0</sub> is the maximum temperature at which the Arrheniusprocess under study does not yet occur.
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