Influence of chemical reactions

Influence of Chemical Reactions on Uq and When a chemical reaction occurs, the transfer rate may be influenced by the chemical reac tion as well as by the purely physical processes of diffusion and convection within the two phases. Since this situation is common in gas absorption, gas absorption will be the focus of this discussion. One must consider the impacts of chemical equilibrium and reac tion kinetics on the absorption rate in addition to accounting for the effec ts of gas solubility, diffusivity, and system hydrodynamics. 

Inspection of Eqs. (14-71) and (14-78) reveals that for fast chemical reactions which are liquid-phase mass-transfer limited the only unknown quantity is the mass-transfer coefficient /cl. The problem of rigorous absorber design therefore is reduced to one of defining the influence of chemical reactions upon k. Since the physical mass-transfer coefficient /c is already known for many tower packings, it... 

Influence of Chemical Reactions on Air-Water Exchange Rates Fast Reaction... 

Figure 1. Influence of chemical reaction speed on the maximum achievable radiochemical yield. A Chemical yield 100% after 90 minutes, maximum radiochemical yield 67%. ...

Based on the data presented in this chapter, the above equation shows the determinant scale, which makes the detection of one type of reciprocal influence of chemical reactions (chemical interference) or another in the reaction mixture easier. 

J. Adler, A One-Dimensional Theory of Liquid Fuel Rocket Combustion. Part II. The influence of Chemical Reaction, A.R.C. Tech. Rept. No. 20-189, Current Paper No. 446 (1959). 

The equations (3.109), (3.117) or (3.118) and (3.120) for the velocity, thermal and concentration boundary layers show some noticeable similarities. On the left hand side they contain convective terms , which describe the momentum, heat or mass exchange by convection, whilst on the right hand side a diffusive term for the momentum, heat and mass exchange exists. In addition to this the energy equation for multicomponent mixtures (3.118) and the component continuity equation (3.25) also contain terms for the influence of chemical reactions. The remaining expressions for pressure drop in the momentum equation and mass transport in the energy equation for multicomponent mixtures cannot be compared with each other because they describe two completely different physical phenomena. 

The influence of chemical reactions on elastic scattering has been extensively studied in the past. Nearly all treatments are based on the optical model (for a review see Ross and Green, 1970). Both the imaginary part of the potential (here assumed to be local) and the opacity function have been parameterized (Mariott and Micha, 1969 Harris and Wilson, 1971 and references cited therein). For a study of the total cross section see Diiren et al. (1972), A semiclassical study of a bimolecular exchange reaction where the three atoms are constrained to move on a straight line but the whole system is free to rotate in three dimensions, predicts a new kind of rainbow (Connor and Child, 1970),... 

Finally, the influence of chemical reactions on sample dispersion should be stressed again. After reaction, the reagents are converted into another species with a different Dm value in the specified medium, thus influencing the dispersion [79]. 

Alteration due to reactions between basalt and hydrothermal solution ( ambient seawater) below the seafloor in massive sulfide ore deposits has been studied extensively, and the physical relationship of a hydrothermal flow zone to such deposits is understood in general terms (13). However, the potential influence of chemical reactions in such stockwork zones on venting solutions and processes of massive sulfide deposit formation has been largely unrecognized. In examining affects on sulfur isotopic composition of the hydrothermal solution, the components of such reactions which may result in sulfate reduction are of primary interest. 

Finally, the relations describing the influence of chemical reactions on the average energy of vibrational modes can be presented as... 

The application of alkali metals at high temperatures can utilize chemical properties, or may be influenced by chemical reactions. The solutions of non-metallic elements in the alkali metals change physical properties of the pure metals. Dissolved elements are able to cause or to influence the corrosion phenomena. Some compounds are only formed or made stable in the presence of excess liquid alkali metal. Due to such an influence of chemical reactions on the behavior or metals, the new applications have initiated many studies in alkali metal chemistry. Interest has been concentrated on the elements lithium and sodium. The heavier alkali metals have found further interest in more recent work. 

In considering the transport of a species from a fluid in turbulent flow toward a solid surface, for example, an electrochemically active species to an electrode, Nemst assumed that the transport was governed by molecular diffusion through a stagnant film of fluid of thickness 6. This model, although having questionable physical relevance, is quite useful for correlating effects such as the influence of chemical reaction on mass transfer. A few simple examples of the use of film theoiy to describe mass transfer in the presence of chemical reaction are considered here. 

E. Mass-Transfer Considerations. The earliest application of the theories of mass transfer to gas absorption did not recognize the influence of chemical reaction in the liquid phase on mass-transfer coefflcients. This influence is explained in the film and penetration theories of absorption by showing that the concentration of the absorbate is depressed everywhere near the gas-liquid interface by its reaction. The interfacial concentration gradient is sharper as a result, and this increases the liquid-phase mass-transfer coefficient. 

The principle for these methods for various electron transfer processes was treated in chapter 2. The influence of chemical reaction on the resulting voltammograms is object of the following paragraphs. Three methods will be discussed here ... 

Figure 4.6.6 Combined model (shrinking core with influence of chemical reaction).

Tang, D., Kern, C., and Jess, A. (2004) Influence of chemical reaction rate, difiusion and pore structure on the regeneration of a coked Al20j-catalyst. Appl. Catal. A Gen., 272, 187-199. 

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