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** Chemical kinetics reaction rates **

** Chemical reaction kinetics reactions **

** Chemical reaction rate coefficients **

From the standpoint of chemical reaction kinetics, Kono (1968) and Kono and Asai (1968, 1969a,b) derived equations for growth and production rate that include a so-called consumption activity coefficient, (j>. The equation is more flexible than the simple Monod relation, and the growth rate is given by [Pg.219]

As for all chemical kinetic studies, to relate this measured correlation function to the diffusion coefficients and chemical rate constants that characterize the system, it is necessary to specify a specific chemical reaction mechanism. The rate of change of they th chemical reactant can be derived from an equation that couples diffusion and chemical reaction of the form (Elson and Magde, 1974) [Pg.117]

The direct proportionality of the dissolution time with the particle size corresponds with the first mechanisms. That means that chemical reaction kinetics have to be rate determining. (Note that in the second mechanism, the mass transfer coefficient k is dependent on / ). [Pg.141]

Chemical reaction rates, 14 607. See also Kinetic measurements Chemical reactions. See also Chemical processes Reaction entries with absorption, 2 47-48, 71-76 activated carbon for control of, 4 755 on adsorbents, 2 629-630, 650-651 atomic level of, 16 736 contexts of, 22 336 engine knock and, 22 390—391 heterogeneous, 22 331-332, 339 homogeneous, 22 339 independent and dependent, 22 336—337 mass-transfer coefficients with, 20 753-755 [Pg.169]

Xij T) describes the probability of finding a molecule in state j at time r, given that it was in state i at time 0. M is the number of species participating in the chemical reaction, and represents the corresponding matrix of the kinetic rate coefficients. G, denotes the average concentration of state i. [Pg.158]

Two distinct approaches have been used to model precursor state kinetics. (1) A successive site statistical model, introduced by Kisliuk [426] for adsorption and adapted by King [298] for desorption. (2) The chemical reaction kinetics approach, involving rate coefficients and the stationary state approximation, followed by Becker and Hartman [424], Ehrlich [425] and recently developed by Gorte and Schmidt [297] and Cassuto and King [421], It has recently been shown by Schon-hammer [427] and Cassuto and King [421] that the two approaches produce the same kinetic expressions. Variants of these models have [Pg.65]

Certainly, most reactor models are semi-empirical. Starting from strong physical and chemical bases, model equations are obtained and, typically, an ordinary differential equations (ODE) or partial differential equations (PDE) set has to be solved. In an equation set, parameters usually need to be fitted (for example reaction-kinetics rate coefficients, catalyst adsorption coefficients, heat-transfer coefficients, etc.), and they are calculated using experimental data. Semi-empirical models have three important advantages (Seborg et al., 1989) [Pg.436]

This is our first encounter with the use of simulation to analyze CV results. Through the theory of simulation (Chapters 4-6), a cyclic voltammetric or potential step response can be calculated for any electrochemical mechanism, given the parameters that describe the experiment (scan rate, scan range, electrode area) and the mechanism (reduction potentials, electrode kinetics, chemical reaction kinetics, and diffusion coefficients of all chemical species). The unknown parameters of the electrochemical mechanism can be varied until a simulation is obtained that closely resembles the experimental result. [Pg.73]

Feb. 22,1879, Varde, Denmark - Dec. 17,1947, Copenhagen, Denmark) Ph.D. Copenhagen 1908, since 1908 Professor of Chemistry (the 3 chair, i.e., the chair of Physical Chemistry at the Univ. of Copenhagen). 1926/27 visiting Professor at Yale Univ., New Haven, Connecticut, USA. Famous for his work on chemical reaction kinetics, chemical affinity, indicators, and thermodynamics of solutions. He could explain the effect of activity coefficients on reaction rates in solutions. In 1923 he developed independently of Lowry, and -> Bjerrum a new -> acid-base theory, the so-called Bronsted acid-base theory. [Pg.59]

Lawrence Stamper Darken (1909-1978) subsequently showed (Darken, 1948) how, in such a marker experiment, values for the intrinsic diffusion coefficients (e.g., Dqu and >zn) could be obtained from a measurement of the marker velocity and a single diffusion coefficient, called the interdiffusion coefficient (e.g., D = A ciiD/n + NznDca, where N are the molar fractions of species z), representative of the interdiffusion of the two species into one another. This quantity, sometimes called the mutual or chemical diffusion coefficient, is a more useful quantity than the more fundamental intrinsic diffusion coefficients from the standpoint of obtaining analytical solutions to real engineering diffusion problems. Interdiffusion, for example, is of obvious importance to the study of the chemical reaction kinetics. Indeed, studies have shown that interdiffusion is the rate-controlling step in the reaction between two solids. [Pg.86]

The variation of efficiencies is due to interaction phenomena caused by the simultaneous diffusional transport of several components. From a fundamental point of view one should therefore take these interaction phenomena explicitly into account in the description of the elementary processes (i.e. mass and heat transfer with chemical reaction). In literature this approach has been used within the non-equilibrium stage model (Sivasubramanian and Boston, 1990). Sawistowski (1983) and Sawistowski and Pilavakis (1979) have developed a model describing reactive distillation in a packed column. Their model incorporates a simple representation of the prevailing mass and heat transfer processes supplemented with a rate equation for chemical reaction, allowing chemical enhancement of mass transfer. They assumed elementary reaction kinetics, equal binary diffusion coefficients and equal molar latent heat of evaporation for each component. [Pg.2]

** Chemical kinetics reaction rates **

** Chemical reaction kinetics reactions **

** Chemical reaction rate coefficients **

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