5. Conclusion

Can we hope to account for the kinetic behavior of any reactive system using the laws in Box 2? It would be presumptuous to say so, unless we operate within a reasonably restricted range of concentrations and temperatures and, consequently, of reaction times and conversion rates.

Indeed, many reactions, especially radical and heterogeneous catalysis reactions, proceed according to complex mechanisms which either lead to mathematically different rate expressions from those of the laws in Box 2, or - and this is the most frequent case - have to be treated numerically because it is not possible to establish analytical expressions for the kinetic laws.

Last but not least, in addition to physical kinetics phenomena such as diffusion, reaction speeds are sensitive to the non-ideality of the reaction medium, pressure, etc.

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