Stoichiometry stoichiometric factor

In this case, the stoichiometric factor is one. This is a measure of the MCD obtained from the DEC consumed. To assess the selectivity losses, the MCD produced in the primary reaction is split into that fraction that will become final product and that which will become the byproduct. Thus the reaction stoichiometry is ... 

Stoichiometric factor z. Which method should be applied for determining the stoichiometry of a direct reaction between ozone and compound (M) The following method is proposed dissolve compound M as well as ozone in independent vessels, mix the two solutions making sure that c(M)0 > 4-10 cLo and let them react until ozone is completely used. ... 

Fig. 7. Proposed function of electrochemical H and Na" potentials in energy conservation coupled to CH4 formation from CO2/H2. The Na+/H antiporter is involved in the generation of from A/iNa ". CHO-MFR, formyl-methanofuran CH2=H4MPT, methylene-tetrahydromethanopterin CH3-H4MPT, methyl-tetrahydromethanopterin CH3-S-C0M, methyl-coenzyme M. The hatched boxes indicate membrane-bound electron transport chains or membrane-bound methyltransferase catalyzing either Na or translocation (see Figs. 5, 6 and 12). ATP is synthesized via membrane-bound H -translocating ATP synthase. The stoichiometries of Na" and translocation were taken from refs. [105,107,167]. x, y and z are unknown stoichiometric factors.

As you practice working with chemical stoichiometry, remember that you will always use a stoichiometric factor at some point. 

The degree of conversion describes whether the ionic sites of the component in deficiency are completely bound by the oppositely charged polyelectrolyte or low molecular counterions remain partly in the complex. Another characteristic quantity of a PEC is its end point stoichiometry, i.e., the molar ratio /E = [A ]E/[C+]E at the end of the complex formation reaction. However, this ratio may be different at other mixing ratios X, so that we have to introduce the stoichiometric factor/(A) = [A ]X/[C+]X to describe the overall composition of the PEC structures at any mixing ratio. 

The results obtained for the fresh and aged commercial Pt/Rh and Pd/Rh TWCs are shown in Table 2. The first column contains the dispersions and calculated spherical particle sizes (in parentheses) derived from the CO methanation technique based on an assumed adsorption stoichiometry of 1 CO per exposed noble metal atom. The arbitrary choice of a stoichiometric factor of 1, rather than the value of 0.7 suggested by the EmoPt-l catalyst, was made on the basis of several factors. The main reason is that the presence of Rh in these catalysts (16% and 10% of the noble metal weight in the Pt/Rh and Pd/Rh catalysts, respectively) is likely to increase the average stoichiometric factor above 0.7 due to the presence of gem-dicarbonyl species on Rh. Bimetallic Pt/Rh particles have been found in automotive catalysts, sometimes with surface enrichment by Rh [20,21] or even bulk enrichment of selected particles as... 

The central conversion factor in Example 4-10 is the same as in previous stoichiometry problems—the appropriate stoichiometric factor. What differs from previous examples is that we use molarity as a conversion factor from solution volume to number of moles of reactant in a preliminary step preceding the stoichiometric factor. 

Other Practical Matters in Reaction Stoichiometry— Stoichiometric calculations sometimes involve additional factors, including the reaction s actual yield, the presence of by-products, and how the reaction or reactions proceed. For example, some reactions yield exactly the quantity of product calculated—the theoretical yield. When the actual yield equals the theoretical yield, the percent yield is 100%. In some reactions, the actual yield is less than the theoretical, in which case the percent yield is less than 100%. Lower yields may result from the formation of by-products, substances that replace some of the desired product because of reactions other than the one of interest, called side reactions. Some stoi-... 

Such problems as this one involve many steps or conversions. Try to break the problem into simpler ones involving fewer steps or conversions. It may also help to remember that solving a stoichiometry problem involves three steps (1) converting to moles, (2) converting between moles, and (3) converting from moles. Use molarities and molar masses to carry out volume-mole conversions and gram-mole conversions, respectively, and stoichiometric factors to carry out mole-mole conversions. The stoichiometric factors are constructed from a balanced chemical equation. 

The overfired batch conversion process, as well as the combustion process, of wood fuels is shown to be extremely dynamic. The dynamic ranges for the air factor of the conversion system is 10 1 and for the stoichiometric coefficients is CHs.iOiCHoOo during a batch for a constant volume flux of primary air. The dynamics of the stoichiometry indicates the dynamics of the molecular composition of the conversion gas during the course of a run. From the stoichiometry it is possible to conclude that... 

We repeat that the procedure we foUow is first to write the reaction steps with a consistent stoichiometry and then to express the rate of each reaction to be consistent with that stoichiometry. Thus, if we wrote a reaction step by multiplying each stoichiometric coefficient by two, the rate of that reaction would be smaller by a factor of two, and if we wrote the reaction as its reverse, the forward and reverse rates would be switched. 

For a reaction in which the stoichiometric relation between analyte and product is not 1 1, we must use the correct stoichiometry in formulating the gravimetric factor. For example, an unknown containing Mg2+ (atomic mass = 24.305 0) can be analyzed gravimetrically to produce magnesium pyrophosphate (Mg2P207. FM 222.553). The gravimetric factor would be... 

A/iAg as a function of time with a single and spatially fixed sensor at , or one can determine D with several sensors as a function of the coordinate if at a given time [K.D. Becker, et al. (1983)]. An interesting result of such a determination of D is its dependence on non-stoichiometry. Since >Ag = DAg d (pAg/R T)/d In 3, and >Ag is constant in structurally or heavily Frenkel disordered material (<5 1), DAg(S) directly reflects the (normalized) thermodynamic factor, d(pAg/R T)/ In 3, as a function of composition, that is, the non-stoichiometry 3. From Section 2.3 we know that the thermodynamic factor of compounds is given as the derivative of a point defect titration curve in which nAg is plotted as a function of In 3. At S = 0, the thermodynamic factor has a maximum. For 0-Ag2S at T = 176 °C, one sees from the quoted diffusion measurements that at stoichiometric composition (3 = 0), the thermodynamic factor may be as large as to 102-103. 

Considerable evidence exits of the survival of Zintl ions in the liquid alloy. Neutron diffraction measurements [5], as well as molecular dynamics simulations [6, 7], give structure factors and radial distribution functions in agreement with the existence of a superstructure which has many features in common with a disordered network of tetrahedra. Resistivity plots against Pb concentration [8] show sharp maxima at 50% Pb in K-Pb, Rb-Pb and Cs-Pb. However, for Li-Pb and Na-Pb the maximum occurs at 20% Pb, and an additional shoulder appears at 50% Pb for Na-Pb. This means that Zintl ion formation is a well-established process in the K, Rb and Cs cases, whereas in the Li-Pb liquid alloy only Li4Pb units (octet complex) seem to be formed. The Na-Pb alloy is then a transition case, showing coexistence of Na4Pb clusters and (Pb4)4- ions and the predominance of each one of them near the appropiate stoichiometric composition. Measurements of other physical properties like density, specific heat, and thermodynamic stability show similar features (peaks) as a function of composition, and support also the change of stoichiometry from the octet complex to the Zintl clusters between Li-Pb and K-Pb [8]. 

Whenever the kinetics of a chemical transformation can be represented by a single reaction, it is sufficient to consider the conversion of just a single reactant. The concentration change of the remaining reactants and products is then related to the conversion of the selected key species by stoichiometry, and the rates of production or consumption of the various species differ only by their stoichiometric coefficients. In this special case, the combined influence of heat and mass transfer on the effective reaction rate can be reduced to a single number, termed the catalyst efficiency or effectiveness factor rj. From the pioneering work of Thiele [98] on this subject, the expressions pore-efficiency concept and Thiele concept have been coined. 

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