Homogeneous reactions steady state

There are many types of chemical reactors which operate under various conditions, such as batch, flow, homogeneous, heterogeneous, steady state, etc. Thus, one general mathematical description which would apply to all types of reactors would be extremely complex. The general approach for reactor design, therefore, is to develop the appropriate mathematical model which will describe the specific reaction system for that particular form of reactor under consideration. For example, if the reaction system is to be evaluated for steady-state... 

In order to study the influence of surface disorder in the MM reaction, Frachenbourg et al. [91] have considered a substratum which has two types of randomly distributed sites with different adsorption rates. It is found that such a kind of disorder can sustain a reactive steady state, in contrast to the standard MM process on homogeneous surfaces. 

R35 can occur in the dark before illumination begins, which will accumulate the radical precursor and help to start the photochemistry when illumination commences. It can also occur continuously during the simulated reaction, maintaining a higher steady-state radical concentration than purely homogeneous processes. Another process of uncertain occurrence, cited in older work, is... 

This homogeneous reaction is instantaneous and mixing is limited. As a consequence, at steady state, by measuring the required volume to complete the discoloring of iodine, it is possible to determine the global mixing time very easily. 

Steady-State Diffusion with Homogeneous Chemical Reaction... 

Vocabulary of Terms Used in Reactor Design. There are several terms that will be used extensively throughout the remainder of this text that deserve definition or comment. The concepts involved include steady-state and transient operation, heterogeneous and homogeneous reaction systems, adiabatic and isothermal operation, mean residence time, contacting and holding time, and space time and space velocity. Each of these concepts will be discussed in turn. 

For a homogeneous gas-phase reaction occurring in a plug-flow reactor, explain briefly under what circumstances tlr < 1. Consider each factor affecting this ratio separately. Give an example (chemical reaction + circumstance(s)) for illustration. Assume steady-state operation and... 

Applying the usual steady-state treatment for consecutive first-order reactions kt at 16 torr pressure over the temperature range 597-701 °C is given by 1.8 x 1011 exp(—47,000/Kr) sec Within experimental error, reactions (1) and (2) were homogeneous processes. However, both k2 and k2 were functions of the total pressure in the system. This dependence is shown in Fig. 1. The methyl zinc decomposition is apparently in its second-order region. Therefore, assuming four effective oscillators and a mean temperature of 1050 °K, = Eohs.+i nRT... 

Two-Electron Catalytic Reactions In a number of circumstances, the intermediate C formed upon transformation of the transient species B is easily reduced (for a reductive process, and vice versa for an oxidative process) by the active form of the mediator, Q. This mechanism is the exact counterpart of the ECE mechanism (Section 2.2.2) changing electron transfers at the electrode into homogeneous electron transfers from Q, as depicted in Scheme 2.9. In most practical circumstances both intermediates B and C obey the steady-state approximation. It follows that the current is equal to what it would be for the corresponding EC mechanism with a... 

The term on the left side of the equation is the accumulation term, which accounts for the change in the total amount of species iheld in phase /c within a differential control volume. This term is assumed to be zero for all of the sandwich models discussed in this section because they are at steady state. The first term on the right side of the equation keeps track of the material that enters or leaves the control volume by mass transport. The remaining three terms account for material that is gained or lost due to chemical reactions. The first summation includes all electron-transfer reactions that occur at the interface between phase k and the electronically conducting phase (denoted as phase 1). The second summation accounts for all other interfacial reactions that do not include electron transfer, and the final term accounts for homogeneous reactions in phase k. 

FIA is a fixed-time analytical methodology, since neither physical equilibrium (homogenization of a portion of the flow) nor chemical equilibrium (reaction completeness) has been attained by the time the signal is detected. The operational timing must be highly reproducible, because the measurements are made under non-steady-state conditions, so that small changes may give rise to serious errors in the results obtained. 

In order to understand the fundamental concept of the cause of temperature sensitivity, in the analysis described in this section it is assumed that the combustion wave is homogeneous and that it consists of steady-state, one-dimensionally successive reaction zones. The gas-phase reaction occurs with a one-step temperature rise from the burning surface temperature to the maximum flame temperature. 

Equipment in which homogeneous reactions are effected can be one of three general types the batch, the steady-state flow, and the unsteady-state flow or semibatch reactor. The last classification includes all reactors that do not fall into the first two categories. These types are shown in Fig. 4.1. 

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