Phase-value ratio

Phase-value ratio depends upon the following factors dispersed phase contents, number and size occlusion, and degree of reactivity. 

The ratio of Eq. (8.66) to Eq. (8.67) gives the ratio of the concentrations of n-mers in phases P and Q f p/f g = Re ". Taking this ratio to be unity for n = 200 gives Re (200) = which is readily solved for A using the R values given. Once these A values are obtained, f p/f g can be evaluated for the required n values. For the phase volume ratios under consideration, the corresponding values of A are listed below also tabulated are the ratios f p/f g for the various n s ... 

However, as stated above, the partition coefficients measured by the shake-flask method or by potenhometric titration can be influenced by the potenhal difference between the two phases, and are therefore apparent values which depend on the experimental condihons (phase volume ratio, nature and concentrahons of all ions in the solutions). In particular, it has been shown that the difference between the apparent and the standard log Pi depends on the phase volume raho and that this relationship itself depends on the lipophilicity of the ion [80]. In theory, the most relevant case for in vivo extrapolation is when V /V 1 as it corresponds to the phase ratio encountered by a drug as it distributes within the body. The measurement of apparent log Pi values does not allow to differentiate between ion-pairing effect and partihoning of the ions due to the Galvani potential difference, and it has been shown that the apparent lipophilicity of a number of quaternary ion drugs is not due to ion-pair partitioning as inihally thought [80]. 

In the above example e is equal to 0.830. The AG of the overall reaction can be expressed in terms Of the corresponding battery voltage and for the hydrogen-oxygen reaction at 25 C, its value is 1.229 V. As the temperature increases this thermodynamic equilibrium value will decrease by a factor of 0.84 mV per C. If the water produced remains in the gas phase, the ratio of AG /AH increases to 0.911. So as we see, these values are much higher than what can be obtained by a heat engine where the efficiency is defined by the ratio of the temperature difference of the hot... 

The definition of friction factor using mean fluid properties has been most widely used because it reduces to the correct single-phase value for both pure liquid and pure gas flow. This technique is very similar to the so-called homogeneous model, because it has a clear physical significance only if the gas and liquid have equal velocities, i.e., without slip. Variations of this approach have also been used, particularly the plotting of a ratio of a two-phase friction factor to a single-phase factor against other variables. This approach is then very similar to the Lockhart-Martinelli method, since it can be seen that (G4)... 

There is some evidence to suggest that, depending upon the phase volume ratios employed, the emulsification technique used can be of greater importance in determining the final emulsion type than the H LB values of the surfactants themselves [434], As an empirical scale the HLB values are determined by a standardized test procedure. However, the HLB classification for oil phases in terms of the required HLB values is apparently greatly dependent on the emulsification conditions and process for some phase-volume ratios. When an emulsification procedure involves high shear, or when a 50/50 phase volume ratio is used, interpretations based on the classical HLB system appear to remain valid. However, at other phase-volume ratios and especially under low shear emulsification conditions, inverted, concentrated emulsions may form at unexpected HLB values [434]. This is illustrated in Figures 7.4 and 7.5. 

K value Ratio of the concentration of a given component in the vapor phase to its concentration in the liquid phase when the phases are in equilibrium. 

In Fig. 2, the weight ratio mx/m2 of hydrocarbon to water is plotted as a function of the concentration of surfactant in the continuous phase (in weight percent) when sodium dodecyl sulfate (SDS) is employed as emulsifier. The above ratio is calculated for the point at which a small amount of hydrocarbon remains as a distinct phase. The ratio mjm2 depends upon the nature of the hydrocarbon employed and increases with the surfactant concentration, more rapidly at lower concentrations. A similar behavior was observed for a non-ionic surfactant, Triton X-100 (Fig. 3), but the values of mllm2 are smaller in this case than in Fig. 2. This happens because the electrostatic repulsion responsible for the stability of the concentrated emulsion containing SDS is stronger than the steric repulsion involved in the stability of the emulsion containing Triton X-100. 

When a 1 10 mole ratio solution of COS in propylene was irradiated in the solid phase at liquid nitrogen temperature, in addition to a minor unidentified product, the three principal gas phase products, MVM, AM, and PS, were formed in a relative yield of 0.10 0 0.34 1.00, respectively. The corresponding gas phase values were 0 21 0.25 1.00. 

We only give basic directions for the choice of a solvent system. If the polarities of the solutes are known, the classification established by Ito [1] can be taken as a first approach. He classified the solvent systems into three groups, according to their suitability for apolar molecules ( apolar systems), for intermediary polarity molecules ( intermediary system), and for polar molecules ( polar system). The molecule must have a high solubility in one of the two immiscible solvents. The addition of a third solvent enables a better adjustment of the partition coefficients. When the polarities of the solutes are not known. Oka s [8] approach uses mixtures of n-hexane (HEX), ethyl acetate (EtOAc), n-butanol (n-ButOH), methanol (MeOH), and water (W) ranging from the HEX-MeOH-W, 2 1 1 (v/v/v) to the n-BuOH-W, 1 1 (v/v) systems and mixtures of chloroform, methanol, and water. These solvent series cover a wide range of hydrophobicities from the nonpolar n-hexane-methanol-water system to the polar n-butanol-water system. Moreover, all these solvent systems are volatile and yield a desirable two-phase volume ratio of about 1. The solvent system leading to partition coefficients close to the unit value will be selected. 

The ratio of the cross-sectional area of the stationary-phase layer to that of the coil tube SISc) governs the volume of the stationary phase retained in the column. The theoretical dependence of SI Sc on the rotation speed 0) and the experimental dependencies of the Sf value (ratio of the volume of the stationary phase retained in the column to the total column volume) on co for n-decane-water and chloroform-water liquid systems are in good agreement (Fig. 1). 

Determined from average of gas-phase values from p. 151 of Reference 10, multiplied by average of liquid/gas ratios on p. 162. 

Both the In k values and the sorption enthalpies, AHm s, may be determined experimentally from the temperature dependence of retention. To calculate the sorption entropy, the phase volume ratio must be known. However, the thermodynamic data may be regarded simply as formal quantities, since the capacity factors correlate directly with AGm >s via the distribution coefficient according to Eq. (38), and since sorption exhibits both distributive and adsorptive character. 

Figure 5. Recovery of YADH activity as a function of pH. Optimum pH for recovery is in the range 4.8-5.2. Phase volume ratio was 1.38. Because of the rapid denaturation of YADH at pH values below 5, all subsequent affinity extractions were carried out at a pH between 5.0 and 5.1.

In eases where the element to be determined is not completely extracted into the organie phase, beeause its partition eoefficient is too low, and the percent of extraction varies depending on the phase-volume ratio, the value of e should be specified along with the extraction conditions (phase-volume ratio, multiplicity of extractions). Despite the fact that a fraction of the analyte remains in the aqueous phase, the whole quantity of the element present in the initial solution is taken into account. 

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