Side reactions rate constants

Fig. 8.12 Parabolic reaction rate constant for the formation of LijSb under three different conditions at the opposite side (a) Ou corresponds to that of the equilibrium LijSb/LijSb, (b) Ou = 10 , (c) Ou = 1.

The units of the reaction rate constant depend on the order of reaction. The units can be determined by knowing that the left-hand side must have a unit... 

In the amorphous tram- and the side vinyl polybutadienes, the first-order reaction rate constants (Table III) give high initial yields (G0) for olefin disappearance when the initial concentration is inserted in the rate equation kD = n(CJCD), where k = rate constant, C = initial concentration, and CD = concentration after dose D. The activation energies for the disappearance of both these olefinic species range from 3.4 to 4.0 keal. per mole, not very different from the activation energy observed for cis disappearance. 

The design of packed column reactors is very similar to the design of packed columns without reaction (Volume 2, Chapter 12). Usually plug flow is assumed for both gas and liquid phases. Because packed columns are used for fast chemical reactions, often the gas-side mass transfer resistance is significant and needs to be taken into account. The calculation starts on the liquid side of the gas-liquid interface where the chemical reaction rate constant is compounded with the liquid side mass transfer coefficient to give a reaction-enhanced liquid-film mass transfer... 

Table 1 presents several examples of unsteady-state kinetics models. These models are presented in the form of rate dependencies for catalytic reaction stages and side processes. The parameters of the models, such as reaction rate constants and activation energies, are given in references (Table 1) and were determined mainly from experimental data using transient response techniques. For the reaction of CO oxidation over a supported platinum catalyst, the kinetic gas theory was applied for estimating the adsorption constants. 

The dynamic behaviour of the 2-hydroxy oxime and its adsorptivity at the interface were well depicted by the molecular dynamics (MD) simulations [34]. It was revealed that the polar groups of —OH and =N—OH of the adsorbed 2-hydroxy oxime molecule were accommodated in the aqueous phase side so as to react with the Ni(II) ion in the aqueous phase [35]. This was thought to explain that the magnitude of the reaction rate constants of Ni(II) at the heptane/water interface and that in the aqueous phase were similar to each other. The diffusive and adsorptive behaviour of LIX65N around the interface was also simulated for 1 ns. The molecule was active around the interfacial region, moving... 

In equation (11), is the reverse reaction rate constant, and it is independent of s. The concentration of vacant states in the semiconductor and the concentration of filled states in the metal has been incorporated into the value of This rate is called the reverse rate, because it represents the formation of the species on the left-hand side of the reaction represented in equation (9). At equihbrium (when = so), these rates must be equal to each other (k = kn so)-... 

Nauser T, Felling J, Schoneich C. (2004) Thiyl radical reaction with amino acid side chains Rate constants for hydrogen transfer and relevance for posttransla-tional protein modification. Chem Res Toxicol 17 1323-1328. 

Morooka (M30), Chiba and Kobayashi (C3), and Drinkenburg and Rietema (D17). According to this approach, the bubble-side film coeflR-cient tends to provide the main resistance to mass transfer when gas adsorption onto the particles is strong and the reaction rate constant is high. The following theory is by Miyauchi and Morooka (M30). 

It is now evident that the order of the initial reaction rate constant will lie between 2 and 3, depending on the relative importance of the first two terms on the right-hand side of Equation (17). In solvents which form hydrogen bonds with the alcohol, the second term will predominate, and at low extent of reaction and low alcohol concentration a second-order reaction will be found. In either case beyond the initial stage the reaction rate is increased by auto-catalysis due to the urethane complex catalysis. 

Laboratory column experiments were used to identify potential rate-controlling mechanisms that could affect transport of molybdate in a natural-gradient tracer test conducted at Cape Cod, Mass. Column-breakthrough curves for molybdate were simulated by using a one-dimensional solute-transport model modified to include four different rate mechanisms equilibrium sorption, rate-controlled sorption, and two side-pore diffusion models. The equilibrium sorption model failed to simulate the experimental data, which indicated the presence of a ratecontrolling mechanism. The rate-controlled sorption model simulated results from one column reasonably well, but could not be applied to five other columns that had different input concentrations of molybdate without changing the reaction-rate constant. One side-pore diffusion model was based on an average side-pore concentration of molybdate (mixed side-pore diffusion) the other on a concentration profile for the overall side-pore depth (profile side-pore diffusion). 

Known OH reaction rate constants and the major-ion composition of seawater combine to imply that OH should react in seawater almost exclusively with bromide ion, with a small amount of side-reaction... 

Note the large differenees in the reaction rate constants independent of whether sulfite or bisulfite is the reagent. This makes the overall process strongly dependent on pH. This pH dependence, however, is much more subtle because the sulfur radieals (sulfite, sulfate and peroxomonosulfate) undergo acid-base equilibrium, whieh likely is on the left-hand side because the hydrogenated species are strong acids ... 

What is the reason for writing a model in the form (5.181) It turned out (Hangos Toth, 1988) that this description makes it easy to estimate the reaction rate constants, because the linear dependence of the right-hand side on the reaction rate constants can be utilised. The estimate can be explicitly given as... 

Figure 15.4 shows how the changing of the rate parameter of the main reaction had a direct effect on the conversion of stearic acid. In order to keep the selectivity of the main reaction constant, the reaction rate constant of the side reaction was adjusted with the same factor used for changing the rate constant of the main reaction. Having the parameter as 0.2 min made the stearic acid concentration to decrease down to 0.3 mol/1. This implied a 90% maximum yield before the deactivation started to dominate and finally decrease the yield down to less than 50%. Having the rate constant as 0.02 min gave only 33% maximum yield and less... 

In this region the diffusion of the complex determines the total permeation rate, which means that the first term on the right-hand side of eq.VI - 85 can be neglected relative to the second term and transport is determined jjy the carrier-solute complex. The Damkohler number can be high even when the reaction rate constant is small, i.e.when the solubility of the solute into the liquid membrane is extremely low. 

Ammonia s3mthesis is a reversible and exothermic reaction without any side reaction. With the rising of temperature the reaction rate constant increases while the equilibrium constant decreases. For a given reactant composition, the reaction rate is affected by two contradictory factors thus there exists an optimum reaction temperature. 

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