Stoichiometry gas phase

Table 8-3. (continued) PFR/PBR Algortthm for Heat Effects 3. Stoichiometry (gas phase, no APy. 

Stoichiometry (gas-phase reaction with no pressure drop) ... 

Stoichiometry. Gas-phase isothermal reaction (r= Tf,) with e = 0. From... 

It was pointed out that a bimolecular reaction can be accelerated by a catalyst just from a concentration effect. As an illustrative calculation, assume that A and B react in the gas phase with 1 1 stoichiometry and according to a bimolecular rate law, with the second-order rate constant k equal to 10 1 mol" see" at 0°C. Now, assuming that an equimolar mixture of the gases is condensed to a liquid film on a catalyst surface and the rate constant in the condensed liquid solution is taken to be the same as for the gas phase reaction, calculate the ratio of half times for reaction in the gas phase and on the catalyst surface at 0°C. Assume further that the density of the liquid phase is 1000 times that of the gas phase. 

P the total pressure, aHj the mole fraction of hydrogen in the gas phase, and vHj the stoichiometric coefficient of hydrogen. It is assumed that the hydrogen concentration at the catalyst surface is in equilibrium with the hydrogen concentration in the liquid and is related to this through a Freundlich isotherm with the exponent a. The quantity Hj is related to co by stoichiometry, and Eg and Ag are related to - co because the reaction is accompanied by reduction of the gas-phase volume. The corresponding relationships are introduced into Eqs. (7)-(9), and these equations are solved by analog computation. 

What happens to the methoxy formed by this process is strongly temperature dependent. At low temperature (up to - 340K) it is stable on the surface and forms the beautiful structures shown in fig.2. Since the active oxygen is used in such reactions then the methoxy must (i) not block the active site at its formation or (ii) diffuses away from the active site. Our evidence indicates the latter to be the case since methoxy is present at sites away from the oxygen islands. Above approximately 340 K the methoxy is unstable and decomposes to yield formaldehyde and hydrogen in the gas phase. Above approximately 400 K, the stoichiometry of the reaction changes to... 

In some specific cases one would like to convert the chemisorption data into an averaged particle size. In that case, the number of surface atoms per unit surface area (density of surface atoms) is an essential parameter. Since this number depends on the type of the crystallographic plane, (see Table 3.7), one also needs information on the types of crystallographic planes exposed to the gas phase. This is also important for another reason the adsorption stoichiometry may depend on the crystallographic plane. 

A tubular reactor is considered in which the gas-phase reaction leads to a change in the molar flow rate and thus in the linear gas velocity. The reaction stoichiometry is represented by... 

On the other hand, electrospray ionization mass spectrometry (ESMS) has been first combined with electrochemistry at ITIES in order to confirm the stoichiometry of a complex ion transferred into an organic phase directly. ESMS is now becoming a popular and powerful technique not only in chemistry but also in biology, pharmacy, medical science, etc. Electrospray (ES) ionization is exceedingly effective resource for producing gas-phase ions from various solutions which contain any kinds of ion. Thus, ESMS can sometimes give us highly useful information in comparison with electrochemical results. 

The stoichiometry and kinetics of gas phase epoxidation of cyclohexene by silica-supported Ti(0 Pr)4 upon treatment with /< r/-butyl hydro peroxide were the... 

No other products were detected in the gas phase. The amount of H2 produced from 85 pmol of m-C16H34 was 4.14 mmol, which is close to the stoichiometric value. One can note that reaction 2.72 stoichiometry resembles that of steam reforming of hexadecane. The authors proposed the following mechanism, which involves the initial generation of active species holes (p+) in the valence band and electrons (e ) in the conduction band of... 

A common way of following the progress of a gas phase reaction with a change in the number of mols is to monitor the time variation of the total pressure, it. From this information and the stoichiometry, the partial pressures of the participants can be deduced, and a rate equation developed in those terms. Usually it is adequate to assume ideal gas behavior, but nonideal behavior can be taken into account with extra effort. Problem P3.03.06 is an example of nonideality. 

A plug flow reactor is used for a reaction with stoichiometry, 2A = 3B, in the gas phase. The rate equation is... 

TABLE II. Results of Volumetric Gas-Phase Analysis for Determination of the CO/Fe Stoichiometry on Titania Samples After Decomposition of Fe (CO)5... 

The usual way to work with this equation is in terms of an equilibrium constant for a reaction. For example, consider a reversible gas-phase reaction of A to form B at a specific rate kj and B reacting back to A at a specific reaction rate The stoichiometry of the reaction is such that v moles of A react to form Vj moles of B. 

The first two determinations by radiation absorption require accurate measurements of the extinction coefficients of ozone (a measurement of the absorption efficiency of the incoming radiation at a maximal absorption wavelength) in the ultraviolet and the infrared. Three different principles have been used over the last 20 years to measure the extinction coefficient of ozone in the ultraviolet at 254 nm manometric, decomposition stoichiometry, and gas-phase titration. The manometric method, which is based on pressure measurements of gaseous ozone, requires (in at least one case ) a substantial and somewhat uncertain correction for decomposition and the method of decomposition stoichiometry depends on the pressure change that accompanies the decomposition of ozone to oxygen, 20, 30,. Clyne and Coxon determined ozone... 

Inn and Tanaka Hearn DeMore and Raper Griggs Gyne and Coxon Becker, Schurath, and Seitz 133 134 135 132 136(250 nm) 135 Manometric Decomposition stoidiiometry Decomposition stoichiometry Manometric Gas-phase titration Manometric... 

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