Predicted K values for

Figure 9. Experimental and BACK-predicted K-values for methane +...

Figure 21. Comparisons of experimental and predicted K values for two gas condensate fluids (----), predicted. (A) (O, , A), Data of Hoff-...

Figure 4.6. shows the ability of the S-R-K correlation to predict K-values for the multicomponent system of 10 species studied experimentally by Yarborough." The data cover more than a threefold range of volatility. Also, the S-R-K correlation appears to be particularly well suited for predicting K-values and enthalpies for natural gas systems at cryogenic temperatures, where the C-S correlation is not always adequate. Figures 4.7 and 4.8, which are based on the data of Cavett" and West and Erbar," are comparisons of K-values computed... 

To be useful for typical petroleum production applications, a state equation must be able to predict the phase behavior of mixtures containing hydrocarbon fractions. The BWRS equation can do this for mixtures containing fractions with molecular weights as high as 500. The BWRS parameters for these fractions are obtained from correlations of the parameters, made dimensionless by dividing by appropriate powers of the critical temperature and critical volume, with the acentric factor. Accurate predicted K-values for light components in oils result from correlations of binary interaction parameters. Reliable simulations of absorber plant... 

As discussed in Sec. 4, the icomplex function of temperature, pressure, and equilibrium vapor- and hquid-phase compositions. However, for mixtures of compounds of similar molecular structure and size, the K value depends mainly on temperature and pressure. For example, several major graphical ilight-hydrocarbon systems. The easiest to use are the DePriester charts [Chem. Eng. Prog. Symp. Ser 7, 49, 1 (1953)], which cover 12 hydrocarbons (methane, ethylene, ethane, propylene, propane, isobutane, isobutylene, /i-butane, isopentane, /1-pentane, /i-hexane, and /i-heptane). These charts are a simplification of the Kellogg charts [Liquid-Vapor Equilibiia in Mixtures of Light Hydrocarbons, MWK Equilibnum Con.stants, Polyco Data, (1950)] and include additional experimental data. The Kellogg charts, and hence the DePriester charts, are based primarily on the Benedict-Webb-Rubin equation of state [Chem. Eng. Prog., 47,419 (1951) 47, 449 (1951)], which can represent both the liquid and the vapor phases and can predict K values quite accurately when the equation constants are available for the components in question. 

Let us estimate a typical value for A. Choosing ta = rt = 5 A, p. = 2 x 10 g,T = 300 K, we find A 4 x 10 M s". This is for the gas phase. In solution the situation is somewhat different because of the solvent cage effect described in Section 4.1. During each bimolecular encounter within a solvent cage, several collisions may occur. This results in a predicted A value for liquid solutions somewhat larger than that for gases. ... 

Now that we have calculated K we can use it to predict the concentrations in an unknown sample from its measured spectrum. First, we place the spectrum into a new absorbance matrix, Aunk. We can now use equation [29] to give us a new concentration matrix, Cunk, containing the predicted concentration values for the unknown sample. 

It is also of interest to mention here that Stevenson s (10) theoretical equation, k = 27r(e2a /ju)1/2 predicts a value for i5 = 3.5 X 10 9. This is close to the experimental value 1.2 X 10 9 discussed in the text and suggests that Stevenson s theoretical equation has some validity for Reactions 15 and 16. Stevenson s equation predicts that i5 and i6 differ... 

Second, due to the difficulty of accessing multiphase flows with laser-based flow diagnostics, there is very little experimental data available for validating multiphase turbulence models to the same degree as done in single-phase turbulent flows. For example, thanks to detailed experimental measurements of turbulence statistics, there are many cases for which the single-phase k- model is known to yield poor predictions. Nevertheless, in many CFD codes a multiphase k-e model is used to supply multiphase turbulence statistics that cannot be measured experimentally. Thus, even if a particular multiphase turbulent flow could be adequately described using an effective viscosity, in most cases it is impossible to know whether the multiphase turbulence model predicts reasonable values for... 

There is a fourth category, consisting of salts that contain the cation of a weak base with the anion of a weak acid. Prediction of the acid—base character of these salts is less obvious, because both ions undergo hydrolysis. The two equilibria not only alter the pH of the solution, but also interfere with each other. Predictions require a comparison of the K values for... 

If the proton donor value Xd) is fixed at 2.58, the equivalent eluent is 54% aqueous acetonitrile and the predicted log/ value for the logP = 3 compounds should be 0.46, which is again different from any of the log/ values in 40% aqueous THF. The dipole moment Xn) of 40% aqueous THF was 2.20 however, such a value cannot be obtained with any proportion of aqueous acetonitrile. To obtain the same log k values as in 40% aqueous THF, a... 

The agreement between the observed and predicted k values of aromatic acids was within 10%. The correlation coefficient was 0.954 (n = 32). An error of greater than 10% for 3-hydroxy-2-naphthoic acid and 2-hydroxybenzoic acid was attributed mainly to an error in their K.A values.25 The partition coefficient, logP, and dissociation constant, pKA, of analytes can be obtained by simple calculations and by computational chemical calculations, and thus the retention time can be predicted in reversed-phase liquid chromatography. 

Many of the projected and actual uses of macrocyclic compounds depend on their marked ion specificities. Consequently, a knowledge of log K values for the interaction between these compounds and cations becomes of utmost importance in predicting their behavior and determining their uses. Macrocyclic compounds should be ideally suited for applications as complexing agents and ion-chelating resins since ring size, number and... 

Using a Kx calculated from AT at p - 61 bar, by using equation (15.12) with j(j)= 1, we predict a value for the formation of NH3 of 2.28 mole percent at 900 K, and 0.093 mole percent at 1600 K. These values are much higher than those obtained experimentally by Nernst. He approached the equilibrium condition from only one direction — by mixing N2 and H2) Kinetics plays an important part in this reaction, and even with catalysts, the reaction is slow unless one goes to high temperatures. It seems probable that Nernst did not achieve equilibrium. 

FIGURE 5.10 Assessment of stability constant (log K) values of the complexes of crown ethers and their acyclic analogs with K+in methanol.25-77 Linear correlations between predicted and experimental log K values for the test set (a) of crown ethers and for the set of acyclic ligands (b) in Figure 5.6a. As QSPR models were built on the training set containing exclusively crown ethers, it is not surprising that predictions for the test set (a) are more reliable. 

The (ATPase)/(kinase) ratio was higher for unlabeled 2,5-anhydromannose than for the deuterated compound by a factor of 1.22, while for the two compounds as substrates for fructo-kinase (ADP production followed) the V/K isotope effect was 1.04 0.02, and there was no V isotope effect. If only the free aldehyde is an activator for the ATPase activity, while the free aldehyde and the hydrate have equal V/K values for the kinase reaction, the predicted isotope effect on the (ATPase)/ (kinase) ratio is 1.19, while that on the V/K for ADP production is 1.024. Thus, the aldehyde is the activator for fructo-kinase as well as for phosphofructokinase. 

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