Initial rate data

There are relatively few kinetic data on the Friedel-Crafts reaction. Alkylation of benzene or toluene with methyl bromide or ethyl bromide with gallium bromide as catalyst is first-order in each reactant and in catalyst. With aluminum bromide as catalyst, the rate of reaction changes with time, apparently because of heterogeneity of the reaction mixture. The initial rate data fit the kinetic expression ... 

Table 3-11 gives the initial rate data [-d(B2Hg)/dt] reported for the gas phase reaetion of diborane and aeetone at 114°C BjHg -i-dMejCO —> 2(Me2CHO)2BH. If a rate expression is of the form Rate = PmcjCO determine n, m, and k. 

In contrast to consecutive reactions, with parallel competitive reactions it is possible to measure not only the initial rate of isolated reactions, but also the initial rate of reactions in a coupled system. This makes it possible to obtain not only the form of the rate equations and the values of the adsorption coefficients, but also the values of the rate constants in two independent ways. For this reason, the study of mutual influencing of the reactions of this type is centered on the analysis of initial rate data of the single and coupled reactions, rather than on the confrontation of data on single reactions with intergal curves, as is usual with consecutive reactions. 

On the basis of regression analysis of the initial rate data obtained for both isolated reactions (Vila) and (Vllb) and for each of the three reactions proceeding in the coupled system [reactions (Vlla)-(VIIc)], of the set of twenty-five equations, the best equation was always found to be of the... 

Very recently, Luckner et al. (116) obtained initial rate data for the metathesis of propene using the W0r-Si02 catalyst at flow rates where mass transfer effects were found to be negligible. Their experimental data referring to measurements at 0.1 to 0.9 MNm-2 and 672 to 727 K could be correlated by Eq. (53). 

Use these initial rate data to estimate the constants in the rate expression... 

The catalyst consists of 3-mm pellets that pack to a bulk density of 1350 kg/m and = 0.5. Mercury porosimetry has found 7 ore = 5nm. The feed mixture to a differential reactor consisted of 5mol% SO2 and 95mol% air. The following initial rate data were obtained at atmospheric pressure ... 

When asked to determine a rate law and rate constant, we must determine the order of the reaction. The rate law for this reaction may contain the concentrations of NO2, F2, and NO2 F raised to powers x, y, and z that must be determined Rate = k [N02] [F2] [NO2 F] Because the rate law contains more than one species, we need to use either isolation or initial rates to determine the orders of reaction. In the experiments whose data are shown, initial rate data are obtained for various combinations of initial concentrations. We apply the ratios of these initial rates to evaluate the orders. 

Using the initial rate data given above do the following (a) Determine the parameters, kR, kH and KA for model-A and model-B and their 95% confidence intervals and (b) Using the parameter estimates calculate the initial rate and compare it with the data. Shah (1965) reported the parameter estimates given in Table 16.14. 

If one has initial rate data available at several different concentrations of species A and at the same initial concentrations of all other species, a more accurate value of fiA may be determined from a log-log plot of equation 3.3.10. In many cases orders determined in this fashion will not... 

One advantage of the initial rate method is that complex rate functions that may be extremely difficult to integrate can be handled in a convenient manner. Moreover, if one uses initial reaction rates, the reverse reactions can be neglected and attention can be focused solely on the reaction rate function for the forward reaction. More complex rate functions may be tested by the choice of appropriate coordinates for plotting the initial rate data. For example, a reaction rate function of the form... 

The following initial rate data [ —d(B2H6)/ dt] were reported for the gas-phase reaction of diborane and acetone at 114 °C. 

Mardaleishvilli, Sin-Chou, and Smorodin-skaya [Kinetics and Catalysis, 8 (664), 1967] have studied the catalytic decomposition of ammonia on quartz. The following initial rate data were obtained by these investigators at 951 C... 

Yang and Hougen Chem. Eng. Progr., 46 (146), 1950] have suggested that initial rate data can be analyzed in terms of total pressure to facilitate the acceptance or rejection of a mechanism. For their analyses, experimental conditions are set such that the two reactants are present in constant composition (often equimolar amounts). 

More initial rate data for monoene substrates have appeared using as catalysts RhCl(CO)P2, HRh(CO)P3 (110, 158), and Rh(NO)P3 (110, 157), where P is a tertiary phosphorus donor. Borohydride reduction of Rh(NO)(PPh3)2Cl gives an active catalyst (159). 

Benzyl alcohol can be produced from benzaldehyde (S) by a dehydrogenation reaction catalyzed by yeast alcohol dehydrogenase (YADH). Nikolova et al. (1995) obtained initial-rate data for this reaction using immobilized YADH immersed in iso-octane with 1% v/v water. The following data were obtained ... 

Data of chemical composition 106 Pressure changes 145 Variables related to composition 164 Half iife and initial rate data 177 Temperature variation. Activation energy Homogeneous catalysis 202 Enzyme and solid catalysis 210 Flow reactor data 222 CSTR data 231 Complex reactions 238... 

Method (c). A portion of the problem can be solved with initial rate data. Thus,... 

P3.02.07. EQUILIBRIUM AND INITIAL RATE DATA A reaction has the rate equation... 

Two series of initial rate data for the reaction between A and B were taken, one with constant pa0 and the other with constant pb0. The pressures are in Torr and r0 is in Torr/sec. 

Initial rate data are reported for the reaction between diborane (A) and acetone (B),... 

An often useful discriminant is initial rate data as a function of total pressure. The equations are simpler because terms for the products are absent. Depending on the results of initial rate analysis, the number of complete equations that may need to be investigated could be narrowed. For instance it may be determined initially if a reactant is adsorbed with or without dissociation. Since the number of possible mechanisms sometimes can be 15 or 20 or more, every bit of preliminary assistance is desirable. Typical initial... 

For the solid catalyzed reaction, 2A B+C, initial rate data were obtained as tabulated, starting with pure A. Consider these three reaction mechanisms,... 

Initial rate data of the catalytic dehydration of butanol-1 are believed controlled by the surface reaction rate with this rate equation in terms of the fugacity, f,... 

Initial rate data for the hydrogenation of ethylene at 41 C were taken by Sussman Potter (Ind Eng Chem 46 457, 1954). Check the validity of the... 

Initial rate data on hydrogenation of benzene over kieselguhr at 173 C and 1 atm were taken by Kehoe Butt (J appl Chem Biotech, p 23, 1972). Check the rate equation,... 

Initial rate data at 350 C with a feed of HC1 and air are tabulated. Units of... 

These initial rate data of an enzyme catalyzed reaction are known ... 

At 415°C, the following initial rate data were recorded. 

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