Equilibrium calculations, comparison

Comparison Theoretical Equilibrium Calculations and Results of Circulation Tests in Porous-Media To make this interpretation more quantitative, the regular solution theory (RST) was applied to sulfonate/desorbent dynamic equilibria reached inside porous media by using the approach described above. In so doing, we assumed that the slugs injected were sufficiently large and that a new equilibrium was reached at the rear of micellar slug in the presence of desorbent. 

According to equilibrium calculations, CO and NO are only important at high temperatures. As the temperature decreases, CO and NO are converted to CO2 and N2, respectively, and the exhaust concentrations are estimated to be below 1 ppm. Furthermore equilibrium calculations indicate that any NO in the exhaust will be present as NO2, and not NO. Comparison with values observed in combustion exhaust shows that neither CO nor NO is in equilibrium. Carbon monoxide emissions range from 10 ppm to 1%, depending on the fuel and the combustion technique. For nitrogen oxides, emissions can be significant from combustion systems and most (about 95%) of the NO emitted is in the form of NO, not N02. 

Nordstrom DK, Plummer LN, Wigley TML, Wolery TJ, Ball JW, Jenne EA, Bassett RL, Crerar DA, Florence TM, Fritz B, Hoffman M, Jr G R Holdren, Lafon GM, Mattigod SV, McDuff RE, Morel F, Reddy MM, Sposito G, Thrailkill J. (1979) Chemical Modeling of Aqueous Systems A Comparison of Computerized Chemical Models for Equilibrium Calculations in Aqueous Systems. Am. Chem. Soc. pp 857-892. 

Nordstrom, D. K., Plummer, L. N., and others. A comparison of computerized chemical models for equilibrium calculations in aqueous systems Jenne, E. A., ed., "Chemical Modeling in Aqueous Systems. Speciation, Sorption, Solubility,... 

A Comparison of Computerized Chemical Models for Equilibrium Calculations in Aqueous Systems ... 

Figure 14.11. Comparison of hematite (a) surface charge (C g ), (b) electrophoretic mobility, and (c) stability ratio, as a function of pH. Note that at pHp the net surface charge and mobility are both zero, and the stability is a minimum. The experimental stability ratio (IFexp). the potentiometrically determined surface charge, and the electrokinetic mobility of 70-nm particles over the pH range from 3 to 11 are shown. The solid line in (c) summarizes experiments obtained with / = 0.05-0.1. (Adapted from Liang and Morgan, 1990.) (d, e) Results of simple equilibrium calculations that have been made with equilibrium constants and surface characteristics of a-Fe203 given by Liang and Morgan (see Example 14.1).

Nordstrom D.K., Plummer L.N., Wigley T.M.L., Wolery T.J., Ball J.W., Jenne E.A., Basset R.L., Crerar D.A., Florence T.M., Fritz B., Hoffman M., Holdren G.R., Jr., Lafon G.M., Mattigod S.V., McDuff R.E., Morel R, Reddy M.M., Sposito G. and Thrailkill J. (1979) A comparison of computerized chemical models for equilibrium calculations in aqueous systems in Chemical Modeling in aqueous systems, speciation, sorption, solubility, and kinetics. Jenne, E.A., ed. Series 93, American Chemical Society, pp. 857-892... 

The rate at which the steam-carbon reaction proceeds depends greatly on temperature (9), requiring heat above 2000°F. to approach equilibrium (II). Since hydrogasification tests are conducted at less than 2000°F. to preserve the methane formed, the carbon-steam reaction is expected to be substantially removed from equilibrium. This is shown by Figure 6 where calculated equilibrium ratios are plotted against maximum bed temperature. The curve represents true equilibrium for comparison. 

Deuteration was also used to investigate the dimer of methionyl-tRNA synthetase [196], Mixture of the deuterated and protonated dimers DD and HH causes hydrid HD dimers to be formed through reversible dissociation. The equilibrium mixture of HH, DD and HD dimers is polydisperse in a //(O) matchpoint graph (cf. ferritin in Section 4.3.1) from which the amount of HD present is calculated. Comparison with the Rq values measured as a function of percentage H20 gave the of monomer and the Parallel Axes Theorem gave the distance between the monomers. 

Fig. 2.9 Comparison of phase equilibrium calculations using SAFT (dashed lines) and PC-SAFT (solid lines) [76]. (a) Vapor-liquid phase equilibrium of polyethylene-toluene at T=393 K. Filled symbols are experimental data for polymer molecular weight...

Figure 6.3 A comparison of experimentally observed OCVs and those predicted by the model and equilibrium calculations with and with out surface carbon formation.

Strategy From the initial concentrations we can calculate the reaction quotient (Q ) to see if the system is at equilibrium or, if not, in which direction the net reaction will proceed to reach equilibrium. A comparison of with also enables us to determine if there will be a depletion in H2 and I2 or HI as equilibrium is established. 

FIGURE 8.15. Comparison of theoretical breakthrough curves for a system with irreversible equilibrium, calculated according to linear rate models with solid and fluid resistances and the solid and pore diffusion models (models 2-5 of Table 8,2). 

Table 3. Comparison of the results of chemical equilibrium calculations for the case of propane oxidation with air at 2200 R and 40 atm. 

In most equilibrium calculations, a quantity y may be neglected in comparison to another quantity z if y is less than 5% of z. 

Vapor Pressure. One of the Important considerations for any equation of state that is to be used for vapor-liquid equilibrium calculations is whether or not it can accurately predict the vapor pressure of pure substances. Table 1 shows a comparison between the PR equation and the Soave-Redlich-Kwong (SRK) equation for predicting the vapor pressure of ten paraffin hydrocarbons and three commonly encountered non-hydrocarbons. 

Comparison of thermodynamic calculations for organic acid decarboxylation reactions with observations from nature and results of laboratory experiments provides an illustration of the application of stable equilibrium calculations to identify the magnitude of kinetic barriers. The law of mass action expression for the acetic acid decarboxylation reaction [Eq. (5)] is given by... 

Nordstrom DK, Plummer LN, Wigley TML, Wolery TJ et al. (1979) A comparison of computerized chemical models for equilibrium calculations in aqueous systems. In Jenne EA (ed) Chemical modeling of aqueous systems I. Am Chem Soc Symp Ser 93, Washington DC, pp 857-892... 

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