Reaction Experiment

Troe J 1975 Unimolecular reactions experiments and theories Kinetics of Gas Reactions ed W dost (New York Academic) p 835... 

Tree J 1975 Unimolecular reactions experiment and theory Physicai Chemistry. An Advanced Treatise vol VIB, ed H Eyring, D Henderson and W Jest (New York Academic) pp 835-929... 

We have demonstrated that due to inhomogeneous distribution of both reaction partners in the micelles, the pseudophase model leads to erroneous estimates of the second-order rate Constantin the micellar pseudophase, so that conclusions regarding the medium of the reaction cannot be derived through this model. However, analysis of substituent effects and endo-exo ratios of the Diels-Alder adducts indicate that the reaction experiences a water-like medium. 

By the collision theory, we expect that increasing the partial pressure (and thus, the concentration) of either the HBr or 02 will speed up the reaction. Experiments show this is the case. Quantitative studies of the rate of reaction (8) at various pressures and with various mixtures show that oxygen and hydrogen bromide are equally effective in changing the reaction rate. However, this result raises a question. Since reaction (8) requires four molecules of HBr for every one molecule of 02, why does a change in the HBr pressure have just the same effect as an equal change in the 02 pressure ... 

Feasibility of HEX Reactors 279 Table 12.8 Operating conditions of oxidation reaction experiments. 

Comparison between the heat exchanged per unit of volume during oxidation experiment in the Shimtec reactor and the maximal heat exchanged in a classical batch reactor (with a double jacket) highlights the effectiveness of the former. Indeed, in oxidation reaction experiments, a mean value of the heat exchanged per unit of volume in the HEX reactor is estimated with utility stream temperature of 47 °C ... 

Reaction experiments were performed at the substrate to catalyst ratios between 250 and 5000 (Table 1). The immobilized catalyst showed a rather constant values of TOP and enantioselectivity in spite of the increase in the S/C ratio, even though these values were slightly lower than those of the homogeneous Ru-BINAP catalyst. After the reaction, the Ru content in the reaction mixture was measured by ICP-AES and was found to be under 2 ppm, the detecting limit of the instrument, indicating the at Ru metal didn t leach significantly during the reaction. These results show that the immobilized Ru-BINAP catalyst had stable activity and enantioselectivity and that the Ru metal complex formed a stable species on the alumina support. 

Thermal desorption spectroscopy and temperature programmed reaction experiments have provided significant insight into the chemistry of a wide variety of reactions on well characterized surfaces. In such experiments, characterized, adsorbate covered, surfaces are heated at rates of 10-100 K/sec and molecular species which desorb are monitored by mass spectrometry. Typically, several masses are monitored in each experiment by computer multiplexing techniques. Often, in such experiments, the species desorbed are the result of a surface reaction during the temperature ramp. 

The Ti02 (001) surface was cleaned and reduced by cycles of ion bombardment as previously described [3]. The distribution of titanium oxidation states was determined from cxirve fitting the Ti(2p3/2) envelope in x-ray photoelectron spectra [3]. After surface preparation, reaction experiments were conducted in either the TPD or steady state mode. TPD experiments have been described [1]. XPS spectra were also obtained following a saturation exposure of the sample using the same procedure as that for the TPD experiments. After pump down, the crystal was placed under the Mg X-ray source and the Ti(2p), 0(ls), and C(ls) regions were scanned. For steady-state experiments a dosing needle was aligned perpendicular to the axis of the mass spectrometer. It was used to direct a steady beam of methylacetylene (Linde, 95%) at the crystal surface when the sample was placed at the aperture of the mass spectrometer. Steady state reaction experiments were... 

The catalyst for the in situ FTIR-transmission measurements was pressed into a self-supporting wafer (diameter 3 cm, weight 10 mg). The wafer was placed at the center of the quartz-made IR cell which was equipped with two NaCl windows. The NaCI window s were cooled with water flow, thus the catalyst could be heated to 1000 K in the cell. A thermocouple was set close to the sample wafer to detect the temperature of the catalyst. The cell was connected to a closed-gas-circulation system which was linked to a vacuum line. The gases used for adsorption and reaction experiments were O, (99.95%), 0, (isotope purity, 97.5%), H2 (99.999%), CH4 (99.99%) and CD4 (isotope purity, 99.9%). For the reaction, the gases were circulated by a circulation pump and the products w ere removed by using an appropriate cold trap (e.g. dry-ice ethanol trap). The IR measurements were carried out with a JASCO FT/IR-7000 sprectrometer. Most of the spectra were recorded w ith 4 cm resolution and 50 scans. 

Figure 5. n-Butane conversion to isobutane as a function of temperature in a temperature programmed reaction experiment conducted over 0.4 g of INiSZ(s) catalyst under an n-butane/ hydrogen mixture (n-C4 molar fraction = 0.34) at a constant heating rate of 2C/min... 

Seinfeld, J.FL, and G.R. Gavalas, "Analysis of Kinetic Parameters from Batch and Integral Reaction Experiments", AIChEJ., 16,644-647 (1970). 

Although polysilanes have been used mostly as photoinitiators for polymerization, they may also find application as initiators for other radical reactions. Experiments to test this possibility are now being carried out. 

The constants k and m may be determined from a log-log plot of the rate versus CA. This procedure leads to a value for the overall order of the reaction. Experiments with nonstoichiometric ratios of reactants can then be used to determine the orders of the reaction with respect to each of the individual species. 

A few facts about the Miller-Urey experiments the now famous original apparatus was modified and improved by Miller himself, and by other groups, in order to improve product yields. In the reaction vessel, temperatures near the reaction zone were between 350 and 370 K, but as high as 870-920 K at the centre of the reaction. Experiments took between several hours and a whole week. The main products (starting with the highest yields) were formic acid, glycine, lactic acid and... 

The luminescent excited state of MogClii reacts rapidly with electron acceptors(24). The powerfully oxidizing MogCli is produced in these reactions. Experiments with BSEP as acceptor in... 

The role of formate in the WGSR will be discussed below. Generally more H2 than CO2 is observed at the end of the reaction. Experiments (26) suggest that this is due to the solubility of CO2 in the solvent system. 

Reactions in which a gaseous product is formed are suitable to investigate in rate of reaction experiments. 

Figure 7 Kinetic analysis of a typical ionogenic reaction (Experiment SGC 9) by means of first and second order plots, p is the ratio [SD ions]t/[SD ions]m. The change of order occurs at about 300 s when p = 70%.

The key to any reaction experiment is moles. The numbers of moles may be calculated from various measurements. A sample may be weighed on a balance to give the mass, and the moles calculated with the formula weight. Or the mass of a substance may be determined using a volume measurement combined with the density. The volume of a solution may be measured with a pipet, or calculated from the final and initial readings from a buret. This volume, along with the molarity, can be used to calculate the moles present. The volume, temperature, and pressure of a gas can be measured and used to calculate the moles of a gas. You must be extremely careful on the AP exam to distinguish between those values that you measure and those that you calculate. 

C after period of the first calibration experiment and fore period of the reaction experiment D main period of the reaction experiment E after period of the reaction experiment and fore period of the second calibration experiment F main period of the second calibration experiment G after period of the second calibration experiment. 

The results of the calibration and reaction experiments are shown in table 8.1 [142]. In this table, t is the time during which a current of intensity /flows through the calibration resistance, V the measured potential drop across the resistance, and m the mass of sample. The values of ATad for the calibration and reaction experiments were determined from the corresponding temperature-time data, using the Regnault-Pfaundler method with 7], Tf, k, and Tc0 calculated from equations 7.12-7.15 (section 7.1). 

Suppose (X 2, (X2)2+, and (X)1 are the organic cations of interest which are involved in the adsorption/desorption reactions experiment. 

Separation experiments on the system Ha-H S. Reaction experiments on the decomposition of hydrogen sulfide over MoSa catalysts packed at tube side. 

Bauer, W., The use of gas/solid fluidization for biocatalysed reactions experiments and modelling, in Ostergaard, K. and Sorensen, A., (eds.). Proceedings of the Fifth International Conference on Fluidization, Elsinore, Denmark, 1986. Engineering Foundation, New York, 619-626. 

In a subsequent experiment, the larger dendritic catalyst 6b was used under optimized eonditions, whieh was expected to result in a slower loss of activity. The results (Fig. 9b) did not show much improvement, indicating that catalyst deactivation was still a major problem. Indeed the number of turnovers (catalytic reaction events) of catalyst 6b was only 260 in the continuous process compared with the value of 3 273 determined in the batch reaction experiment in contrast, the monomeric model compound showed a number of turnovers of 6 027. 

Cleland and Wilhelm (C18) used a finite-difference technique which could be used for nonlinear reactions, but they limited their study to a first-order reaction. Experiments were also performed to test the results of the theory. In a small reaction tube, the two checked quite well. In a large tube there were differences which were explained by consideration of natural convection effects which were due to the fact that completely isothermal conditions were not maintained. This seems to be the only experimental data in the literature to date, and shows another area in which more work is needed. The preceding discussion considered only isothermal conditions except for Chambre (C12) who presented a general method for nonisothermal reactors. 

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