Importance of understanding the

The evaluation of the parameters for this flow regime requires the calculation of the Reynolds number and hydraulic diameter for each continuous phase. The hydraulic diameter can be determined only if the holdup of each phase is known. This again illustrates the importance of understanding the fluid mechanics of two phase systems. Once the hydraulic diameter is known, the Reynolds number can be evaluated with the knowledge of the in situ phase velocity, and the parameters of the model equations can be evaluated. 

The importance of understanding the electron density is made clear by the Hell-mann-Feynman theorem. We will see that this theorem shows us that all the properties of a molecule are ultimately determined by the electron density distribution p. 

Case histories regarding reactive chemicals teach the importance of understanding the reactive properties of chemicals before working with them. The best source of data is the open literature. If data are not available, experimental testing is necessary. Data of special interest include decomposition temperatures, rate of reaction or activation energy, impact shock sensitivity, and flash point. 

We show that the electric field in the metal-solution interphase is very high (e.g., 10 or lO V/cm). The importance of understanding the structure of the metal-solution interphase stems from the fact that the electrodepKJsition processes occur in this very thin region, where there is a very high electric field. Thus, the basic characteristics of the electrodeposition processes are that they proceed in a region of high electric field and that this field can be controlled by an external power source. In Chapter 6 we show how the rate of deposition varies with the potential and structure of the double layer. 

In summary, the diffusion behavior of both H2O and CO2 demonstrates the importance of understanding the role of speciation in diffusion, and the very different consequences due to that role. Diffusion of a single-species component (such as Ar) usually does not depend on its own concentration (when the concentration is low), but depends on the melt composition. For a multispecies component, speciation affects the diffusion behavior. For H2O, speciation makes the diffusion behavior very complicated even at low H2O concentrations, total H2O diffusivity still depends on H2O content (because the species concentrations are not proportional), in addition to the dependence on melt composition. If species concentrations are proportional to each other and hence to the total concentration of the component, then the diffusivity is independent of the concentration of the component, as in the case of CO2 diffusion. Many multispecies components probably satisfy this condition that the concentrations of... 

However, this does illustrate the importance of understanding the fundamental mechanisms in order to extrapolate to atmospheric conditions reliably. A number of experimental techniques used for studying gas-phase kinetics and mechanisms require low pressures and, under these conditions, decomposition of the OH-alkene adduct can predominate. As long as the fundamental mechanisms are understood and the kinetics determined as a function of pressure, extrapolation to atmospheric conditions is possible. Clearly, confirmation using studies at atmospheric pressure is also important. 

The importance of understanding the mechanism of nucleophilic substitution reactions can best be appreciated by studying the distribution of products of the example given above. When 2-bromopropane is allowed to react with the methoxide ion in methanol, less than half of the starting material is converted into methyl isopropyl ether the rest is transformed into 2-propene. 

Differences in the PID algorithm, controller parameters, units, and other fundamental control functions highlight the importance of understanding the structure of the controller and the requirement of sufficiently detailed documentation. This is especially important for the controller but is also important for the field instruments, final control elements, and device tnat have the potential to affect the signal characteristics. 

In the majority of cases, the last step in the preparation of catalytically active metals is a reduction. The precursor is very frequently an oxide. An oxychloride is the real precursor of active platinum and some noble metals if chlorometal complexes (e.g. chloroplatinic acid) are used. It may be advantageous to use still other precursors and to reduce them directly without any intermediary transformation to oxide. On the other hand, nearly all catalytic metals are used as supported catalysts. The only notable exception is iron for ammonia synthesis, which is a very special case and then the huge body of industrial experience renders scientific analysis of little relevance. The other important metals are Raney nickel, platinum sponge or platinum black, and similar catalysts, but they are obtained by processes other than reduction. This shows the importance of understanding the mechanisms involved in activation by reduction. 

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