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Formation equation

Surfactants aid dewatering of filter cakes after the cakes have formed and have very Httle observed effect on the rate of cake formation. Equations describing the effect of a surfactant show that dewatering is enhanced by lowering the capillary pressure of water in the cake rather than by a kinetic effect. The amount of residual water in a filter cake is related to the capillary forces hoi ding the Hquids in the cake. Laplace s equation relates the capillary pressure (P ) to surface tension (cj), contact angle of air and Hquid on the soHd (9) which is a measure of wettabiHty, and capillary radius (r ), or a similar measure appHcable to filter cakes. [Pg.21]

Catalytic reduction of folic acid to 5,6,7,8-tetrahydrofolic acid (225) proceeds fast in trifluoroacetic acid (66HCA875), but a modified method using chemical reductants leads with sodium dithionite to 7,8-dihydrofolic acid (224). Further treatment with sodium borohydride gives (225) which has been converted into 5-formyl-(6i ,S)-5,6,7,8-tetrahydro-L-folic acid (leucovorin) (226) by reaction with methyl formate (equation 70) (80HCA2554). [Pg.307]

If we combine the Gibbs energy of formation equations above to derive the equation... [Pg.267]

If the reductant is insoluble in water but soluble in the mercury phase (amalgam formation), equation (7) still holds. Substituting in equation (3), we have ... [Pg.600]

TABLE 1. Yields of RS02 in the radiolysis of N20-saturated aqueous solutions of symmetrical sulfoxides (R2SO), the percent of OH forming RS02 [G(OH) = 6.0] and the rate constants for ion formation (equation 30)... [Pg.900]

Coefficients, distribution—See Distribution coefficients Coefficients of free energy of formation equation, Pu oxide vapor. 127/... [Pg.457]

For an incoherent source, the observed image y s) in a direction s is given by the standard image formation equation ... [Pg.397]

Considering the diagonalized form (5) of the image formation equation, a very tempting solution is to perform straightforward direct inversion in the Fourier space and then Fourier transform back to get the deconvolved image. [Pg.399]

Tec and rn decrease when the carbon adsorption energy increases. Volcano-type behavior of the selectivity to coke formation is found when the activation energy of C-C bond formation decreases faster with increasing metal-carbon bond energy than with the rate of methane formation. Equation (1.16b) indicates that the rate of the nonselective C-C bond forming reaction is slow when Oc is high and when the metal-carbon bond is so strong that methane formation exceeds the carbon-carbon bond formation. The other extreme is the case of very slow CO dissociation, where 0c is so small that the rate of C-C bond formation is minimized. [Pg.13]

Note the product and reactant terms are the opposite way round to that in the expression for the calculation from heats of formation (equation 3.26). [Pg.80]

In reality, not only the main reaction (the Fischer-Tropsch reaction) leading to the formation of higher hydrocarbons (Equation 12.1), but also methane formation (Equation 12.2) and the water-gas shift reaction (Equation 12.3) have to be considered. The rate equations for these three reactions on a commercial Fe-catalyst were determined by Popp8 and Raak2 and summarized by Jess et al.9 However, to simplify matters, just the Fischer-Tropsch reaction forms the basis of the approach presented here ... [Pg.219]

A comparison of the estimates using Equations 7-18 and 7-19 with the experimental values in Table 7-1 shows that Equation 7-18 predicts a lower oxygen value than the experimental values for all species, with the exception of methyl formate. Equation 7-19 predicts a lower... [Pg.306]

Recently, Yu and co-workers developed an operationally simple catalytic system based on [RuCl2(/>-cymene)]2 for stereoselective cyclization of a-diazoacetamides by intramolecular carbenoid C-H insertion.192 /3-Lactams were produced in excellent yields and >99% m-stereoselectivity (Equation (53)). The Ru-catalyzed reactions can be performed without the need for slow addition of diazo compounds and inert atmosphere. With a-diazoanilide as a substrate, the carbenoid insertion was directed selectively to an aromatic C-H bond leading to y-lactam formation (Equation (54)). [Pg.188]

Silastannative cyclization of bis(diene) catalyzed by PdC cod) achieves formal 1,8-silastannative G-G bond formation (Equation (118)).125 Poor stereoselectivity at the allylic metal moieties (E/Z) is observed. [Pg.776]

When writing defect formation equations, the strategy involved is always to add or subtract elements to or from a crystal via electrically neutral atoms. When ionic crystals are involved, this requires that electrons are considered separately. Thus, if one considers NiO to be ionic, formation of a VNi would imply the removal of a neutral Ni atom, that is, removal of a Ni2+ ion together with two electrons. Similarly, formation of a VQ would imply removal of a neutral oxygen atom, that is, removal of an O1 2- ion, followed by the addition of two electrons to the crystal. An alternative way to express this is to say the removal of an O2- ion together with 2h. Similarly, only neutral atoms are added to interstitial positions. If ions are considered to be present, the requisite number of electrons must be added or subtracted as well. Thus, the formation of an interstitial Zn2+ defect would involve the addition of a neutral Zn atom and the removal of two electrons. [Pg.31]

Reactions involving the creation, destruction, and elimination of defects can appear mysterious. In such cases it is useful to break the reaction down into hypothetical steps that can be represented by partial equations, rather akin to the half-reactions used to simplify redox reactions in chemistry. The complete defect formation equation is found by adding the partial equations together. The mles described above can be interpreted more flexibly in these partial equations but must be rigorously obeyed in the final equation. Finally, it is necessary to mention that a defect formation equation can often be written in terms of just structural (i.e., ionic) defects such as interstitials and vacancies or in terms of just electronic defects, electrons, and holes. Which of these alternatives is preferred will depend upon the physical properties of the solid. An insulator such as MgO is likely to utilize structural defects to compensate for the changes taking place, whereas a semiconducting transition-metal oxide with several easily accessible valence states is likely to prefer electronic compensation. [Pg.32]

For example, the formation of an intrinsic interstitial defect requires the simultaneous creation of a vacancy. These may not remain close together in the crystal, and it is legitimate to consider that the two defects occur in equal numbers. Thus, in silicon it is possible to write the formation equation for silicon self-interstitials, Sii as... [Pg.38]

Chemically, this can be expressed in terms of defect formation equations. Taking the partial pressure of the zinc as dominant, zinc-rich material can be formulated by the capture of zinc atoms from the gas phase ... [Pg.148]

At high temperatures the spinel MgAl204 can take in excess alumina to a composition of approximately 70 mol% A1203 (Fig. 4.5). (a) What are the possible formulas that fit the composition of this spinel Write the defect formation equation for the reaction if the excess A1 is (b) distributed over both magnesium and aluminum sites and (c) only over aluminum sites. Assume that there is no electronic compensation in the insulating oxide. [Pg.201]

The composition of a slightly nonstoichiometric cobalt oxide is C00.999O. (a) Write a defect formation equation for this phase assuming that electronic compensation occurs, (b) If conductivity takes place by hopping, what is the value of the factor cp in Eq. (7.1) ... [Pg.347]

It is important to know that the defect equilibria that apply to the pure material, and the associated equilibrium constants, also apply to the doped material. The only additional information required is the nature and concentration of the dopant. To illustrate the construction of a diagram, an example similar to that given in Chapter 7 will be presented, for a nonstoichiometric phase of composition MX, nominally containing M2+ and X2- ions, with a stoichiometric composition MXl 0. In this example, it is assumed that the relevant defect formation equations are the same as those given in Chapter 7 ... [Pg.358]

An idea of how the conductivity will change over the partial pressure range can be gained by writing out the potential defect formation equations. At high oxygen... [Pg.384]

To establish the stoichiometry of the sulfide formation, Equation (6.3) must be combined with the oxidation process for the organic matter that is the actual electron donor for the heterotrophic sulfate-reducing bacteria. The procedure for the combination of the oxidation and the reduction process steps is the same as outlined in Section 2.1.3. If organic matter is considered simply as CH20, the combination of the oxidation process as depicted in Example 2.2 and the reduction reaction for sulfate shown in Equation (6.3) result in the following redox process ... [Pg.135]

The equilibrium constant of colloid formation (Equation (10.14)) is given by... [Pg.515]

A similar exercise can be made with other anions and cations, producing a list of relative values of standard enthalpies of formation, anchored on Af77°(H+, ao) = 0. This database is rather useful, because it allows the enthalpies of formation (equation 2.53) and the lattice enthalpies (equation 2.47) of many crystalline ionic salts to be predicted, since their solution enthalpies are usually easy to measure. [Pg.30]

Nitrosothiols can also be reduced with sodium borohydride, leading (with SNAP14) to the disulphide formation (equation 18). [Pg.672]


See other pages where Formation equation is mentioned: [Pg.139]    [Pg.857]    [Pg.44]    [Pg.44]    [Pg.668]    [Pg.743]    [Pg.397]    [Pg.398]    [Pg.398]    [Pg.405]    [Pg.668]    [Pg.743]    [Pg.900]    [Pg.983]    [Pg.508]    [Pg.134]    [Pg.139]    [Pg.34]    [Pg.120]    [Pg.670]    [Pg.674]   
See also in sourсe #XX -- [ Pg.6 , Pg.194 ]

See also in sourсe #XX -- [ Pg.6 , Pg.194 , Pg.195 ]

See also in sourсe #XX -- [ Pg.205 ]




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