Graphical representation Arrhenius

Fig. 16. Graphical representation of Arrhenius parameters for the low temperature decomposition of ammonium perchlorate (pelleted, orthorhombic, o, and cubic, , forms). Compensation behaviour is observed. Data from Jacobs and Ng [452]. N = nucleation, B = branching, G = growth processes.

Researchers admit that the Arrhenius equation is applicable to any temperature if similar failure mechanisms occur. In the graphical representation we have placed two temperatures and the lifetimes corresponding to these temperatures. If the two temperatures are selected as usually operating temperatnre Tf, respective as accelerated aging Ta, then the two times will represent the real hfetime tf) and that of accelerated aging ta) imder conditions that simulate the usually operation. 

Therefore, we have utilized a graphic method with a special representation-Arrhenius plot, presented in Fig. 3. The coordinate axes are time at logarithmic scale, on abscise and on the ordinate - the reverse of absolute temperature. In order to simplify the utilization of the Arrhenius plot, the ordinate is scaled with the temperature in C (at a properly calculated scale). 

A standard graphic representation of the Arrhenius model is shown in Fignre 8.25. 

Another feature of the analysis of the temperature dependence of reaction velocities, which has received much attention and frequently dubious interpretation, is the non-linearity of the Arrhenius plot. Moore Pearson (1981) use the term anti Arrhenius plots for some of their graphical representations of rates which first increase and then decrease as the temperature is raised. They state, correctly, that such graphs usually result from multi-step mechanisms or a change in mechanism as the temperature increases. 

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