Surface mole fraction

Figure 2. Surface mole fraction of protonated 4-pyridylcarbinol vs. pH. Points are from SERS spectra obtained at -0.20 V vs.

Figure 11. Surface mole fraction of Ac at a = 0 as a function of the bulk mole fraction of Ac. (I) Ac...

Figure 26.5 Surface mole fractions of fuel and NO as functions of stagnation surface (solid curves) and PSR temper-atirre (dashed curves), for 28% inlet H2 in air (a) and 12% inlet H2 in air (b). The maximum temperature indicates adiabatic operation. The conditions are the same as in Fig. 26.4...

Using this approach, a model can be developed by considering the chemical potentials of the individual surfactant components. Here, we consider only the region where the adsorbed monolayer is "saturated" with surfactant (for example, at or above the cmc) and where no "bulk-like" water is present at the interface. Under these conditions the sum of the surface mole fractions of surfactant is assumed to equal unity. This approach diverges from standard treatments of adsorption at interfaces (see ref 28) in that the solvent is not explicitly Included in the treatment. While the "residual" solvent at the interface can clearly effect the surface free energy of the system, we now consider these effects to be accounted for in the standard chemical potentials at the surface and in the nonideal net interaction parameter in the mixed pseudo-phase. 

Hence the surface adsorption of surfactant 1 and 2, and their surface mole fractions can be obtained from the surface (interfacial) tension-concentration relationships (Fig.1 and fig.2) by applying the Gibbs adsorption equation. 

It is worth noting that at air/water surface the surface mole fraction / ( (CioSNa) is much less than the... 

Ule may calculate the surface adsorptions and surface mole fractions of and CyF from surface tension-concen-... 

The surface mole fraction of CgSOC then is expressed as... 

Okano et al. [78-80] found that HEMA-STY triblock copolymer formed a typical domain structure when it was cast into a film. The domain structure changed with the HEMA mole fraction, and the lamella structured surface (mole fraction of HEMA 0.61 lamella width 30-50 nm) exhibited the best blood-compatibility. 

The surface mole fraction is entirely analogous to the bulk value of this quantity,... 

If the surface mole fraction d of solvent i is defined, the sum of all Ot values (for the various solvents in the mobile phase mixture) must be equal to one. This then allows the calculation of e° for the mobile-phase mixture A/B/C. .. as (15)... 

Equation (39) allows the calculation of the surface mole fraction 6b of B-solvent js a function of Nb, for mobile phases A/B (or A/C). The weight of B-solvent in the adsorbed monolayer at saturation (0 = 1) can be calculated from the B-solvent At, value and its molecular weight (see Refs. 1 and 14). The uptake of B-solvent by the adsorbent for some value of Nb is then given as 6 °- Several studies 4, 12) have reported experimental solvent isotherms (plots of 1 ° versus Af ) for silica, and it is of interest to compare these data with isotherms calculated as above. 

Pan states that CH4 is more reactive than ammonia so that there is likely to be some mass transfer limitation on methane as well as ammonia. Making an assumption that the surface mole fractions of reactants will be of the order of half the bulk gas-phase levels, approximate reaction probabilities for NH3 and CH4 can be calculated. Collision rates are about 2 x 10 molecules cm" s" so that the reaction probability for ammonia and methane is about 10" and for oxygen about 2.5 x 10". These are sufficiently close to the values for independent oxidation of CH4 and NH3 to make it likely that the same surface reactions are also involved in the co-oxidation. 

This expression allows calculation of the fluxes and N2. It must be noted that in problems of this kind one of the surface mole fractions, x q say, will be unknown and given by an expression for the heterogeneous reaction rate at the surface (e.g., = A c X o,... 

Figures 5.38-5.40 show the surface mole fraction for the reacting components and final products. o-Xylene surface mole fraction decreases with the increase in bulk temperature, showing hysteresis with multiple steady states for the range of bulk temperature 650 K to 700 K. The mole fraction of o-Xylene may drop suddenly at the first limit (bifurcation) point or it may continue on the upper branch and...

FIGURE 5.39 Maleic anhydride and product surface mole fractions at the multiplicity region. 

The enrichment of the slow dissolving component, B, in an alloy surface under simultaneous dissolution conditions may be rationalized by a model of alloy dissolution that is based on the simplifying assumptions (1) that a homogeneous solid solution may be described as a heterogeneous dispersion of atomic dimensions with area fraction (surface mole fraction) X j for component j, and (2) that the alloy components dissolve independently. The partial current density ij of an alloy component j will then be given by ij = i -X j, where i is the current density of the pure metal, j, and for a binary alloy A-B, the total current density of alloy dissolution. 

Fig. 17 Cyclic voltammograms for the reductive desorption of various SAMs in 0.5 M KOH solution (a) original phase-separated binary SAM of MPA and HDT where the surface mole fraction of MPA is 0.49 (b) SAM after the selective desorption of MPA (c) regenerated binary SAM of MPA and HDT (d) binary SAM of MUAand HDT after the selective replacement of M PA with MUA. Initial potential, —0.2 V scan rate, 20 mV s electrode area,...

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