Macrokinetic theory

L vov B. V., Bayonov P. A. and Ryabchuk (1981) A macrokinetic theory of sample vaporization in electrothermal atomic absorption spectrometry, Spectrochim Acta, Part B 36 397-425. 

Chemical reactions obey the rules of chemical kinetics (see Chapter 2) and chemical thermodynamics, if they occur slowly and do not exhibit a significant heat of reaction in the homogeneous system (microkinetics). Thermodynamics, as reviewed in Chapter 3, has an essential role in the scale-up of reactors. It shows the form that rate equations must take in the limiting case where a reaction has attained equilibrium. Consistency is required thermodynamically before a rate equation achieves success over tlie entire range of conversion. Generally, chemical reactions do not depend on the theory of similarity rules. However, most industrial reactions occur under heterogeneous systems (e.g., liquid/solid, gas/solid, liquid/gas, and liquid/liquid), thereby generating enormous heat of reaction. Therefore, mass and heat transfer processes (macrokinetics) that are scale-dependent often accompany the chemical reaction. The path of such chemical reactions will be... 

In order to estimate the region of this approximation applicability, it is necessary to examine macrokinetics of a polymeranalogous reaction with explicit allowance for the diffusion of a reagent Z into a globule. In this case, the profile of its constituent monomeric units will be fuzzy rather than stepwise (see Fig. 1). This brings up two questions. The first one is how this profile depends on kinetic and diffusion parameters of a reaction system. The second question is concerned with the effect of the profile shape on the statistical characteristics of the chemical structure of the products of a polymeranalogous reaction. A rigorous theory has been developed [22,23] which enables us to answer these questions. The main concepts of this theory are outlined in the subsequent Sections. 

Prom the standpoint of thermodynamics, the system electrolyte-film-electrode is open and far from equilibrium state. In this study we use the theoretical approach to the description of such systems created by H. Poincare and further developed later by Andronov and others. This method is called bifurcation analysis or, alternatively, theory of non-linear dynamic systems [7]. It has been applied to the studies of macrokinetics (dynamics) of the processes in electrode film systems. 

In addition to the process kinetic formulations of Atkinson, which are derived from the theory of mass transport with simultaneous biological reaction, other kinetic equations, macrokinetic in origin, are also known. 

Major contributions to the development of the macrokinetic or macrohomogeneous theory of porous electrodes were made by Yu, A, Chizmadzhev and Yu, G, Chirkov [25-27], In these works the importance of the interplay of oxygen diffusion and interfacial kinetics had already been realized. For oxygen reduction electrodes, a large electrocatalytically active surface area per unit volume,, has to compensate for the smallness of the intrinsic activity per unit... 

Major contributions to the development of the macrokinetic or macrohomoge-neous theory of porous electrodes were made by Yu. A. Chizmadzhev, Yu.G. Chirkov,... 

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