Solubility and pressure

Fig. 7 Dependence of vapor pressure and solubility for an enantiotropic pair (I/II), a monotropic pair (I/III), and an amorphous compound (a).

Estimate based on vapor pressure and solubility. cMulkey (24). 

By substituting equations for vapor pressure and solubility, the temperature dependence equation for Henry s law constant can be obtained, as demonstrated by Glew and Robertson (1956), Tsonopoulos and Wilson (1983), Heiman et al. (1985), and ten Hulscher et al. (1991). 

When using vapor pressure and solubility data, it is essential to ensure that both properties apply to the same chemical phase, i.e., both are of the liquid, or of the solid. Occasionally, a solubility is of a solid while a vapor pressure is extrapolated from higher temperature liquid phase data. 

Saldana MDA, Tomberli B, Guigard SE, Goldman S, Gray CG and Temelli F. 2007. Determination of vapor pressure and solubility correlation of phenolic compounds in supercritical CO2. J Supercrit Fluids 40(1) 7—19. 

FIGURE 12.2 An illustration of the vapor pressure and solubility effects discussed in the text. Components A, B, and C have vapor pressures decreasing from A to B to C and have solubilities in the stationary phase increasing from A to B to C. 

If a GC operator expects a given mixture component to have a very long retention time compared to other mixture components, what vapor pressure and solubility properties would this mixture component have ... 

Equation (69) is incorrect because, as stressed above, it is the curvature which affects properties such as vapor pressure and solubility, not the actual extents of... 

C.E. presumably affects also some experimental results on the ys. In particular, the effect of particle size on vapor pressure and solubilities, Sections III.6 and III.7, are related to C.E. more than to the true surface energy as already pointed out, small particles usually have a less perfect crystal lattice than do larger crystals. A more direct estimate of C.E. is afforded by the measurements of the heat of dissolution. 

Cohesive Pressure, Internal Pressure, and Solubility Parameter... 

Meissner, H.P. Kusik, C.L., "Aqueous Solutions of Two or More Strong Electrolytes-Vapor Pressures and Solubilities", I EC Process Des. Develop., 1973, 12, 205... 

As already discussed, the KiWi value of a given compound may also be approximated by the ratio of its vapor pressure and its aqueous solubility (Eqs. 6-16 and 6-17). When using this approximation one has to be aware that, particularly for compounds exhibiting very small p L and/or C values, rather large errors may be introduced due to the uncertainties in the experimental vapor pressure and solubility data (see Sections 4.4 and 5.5). 

Because hazardous wastes have different physicochemical properties (vapor pressure and solubility), contaminated media may contain inconsistently distributed pollutants. The distribution depends on environmental conditions and is a function of the properties of the chemical. In general, contaminated media are classified as (1) soil, (2) air, (3) sludge and sediments, and (4) groundwater, and each type may contain pollutants in different phases ... 

Also of interest is the maximum capacity of each phase for chemicals, i.e., the saturation concentration above which phase separation occurs. For water, this is obviously the solubility in water. For many polar substances, the chemical and water are miscible (e.g., ethanol) and no solubility limit exists. Similarly, a solubility limit in octanol may or may not exist. For air, the solubility corresponds to the saturation vapor pressure Ps. This can be converted to a solubility in units of mol / m3 by dividing by RT, the gas constant — absolute temperature product. Chapter 7 discusses solubility in water. Solubility in octanol is not by itself of comparable interest and is not treated. Vapor pressure and solubility in water are not only of fundamental interest, but their ratio H is essentially the Henry s Law constant or air-water partition coefficient, as Chapter 4 discusses. 

Method 1 Estimation from Vapor Pressure and Solubility Data... 

This procedure is not recommended for chemicals soluble in water or vice versa to an extent exceeding a few percent. The vapor pressure and solubility can be of the chemical in a solid or liquid state, depending on the melting point. The same state must apply to both properties. 

Finally, it is possible to estimate or correlate KAW or FI directly from molecular structure, avoiding the separate determination of vapor pressure and solubility. 

Each chemical simulated must have values provided for its vapor pressure and solubility or Henry s constant, Kh, and its organic carbon partition coefficient, Koc an< ts degradation rate, y. 

The quantitative relationship between pressure and solubility is given by Henry s Law ... 

The Henry s law constant, H, calculated from the ratio of vapor pressure and solubility [equation (2.4)] can be converted to the dimensionless Henry s law constant, H, [equation (2.3)] by the expression... 

Interfacing the TEA to both a gas and a HPLC has been shown to be selective to nitro-based explosives (NG, PETN, EGDN, 2,4-DNT, TNT, RDX and HMX) determined in real world samples, such as pieces of explosives, post-blast debris, post-blast air samples, hand swabs and human blood, at picogram level sensitivity [14], The minimum detectable amount for most explosives reported was 4-5 pg injected into column. A pyrolyser temperature of 550°C for HPLC-TEA and 900°C for GC/TEA was selected. As the authors pointed out, GC uses differences in vapour pressure and solubility in the liquid phase of the column to separate compounds, whereas in HPLC polarity, physical size and shape characteristics determine the chromatographic selectivity. So, the authors reported that the use of parallel HPLC-TEA and GC-TEA techniques provides a novel self-confirmatory capability, and because of the selectivity of the technique, there was no need for sample clean-up before analysis. The detector proved to be linear over six orders of magnitude. In the determination of explosives dissolved in acetone and diluted in methanol to obtain a 10-ppm (weight/volume) solution, the authors reported that no extraneous peaks were observed even when the samples were not previously cleaned up. Neither were they observed in the analysis of post-blast debris. Controlled experiments with handswabs spiked with known amounts of explosives indicated a lower detection limit of about 10 pg injected into column. 

Ostwald2 pointed out that, just as the vapour pressure of small drops of liquid is greater than that of large drops, so the vapour pressure and solubility of small solid particles is greater than that of large. The relation between the radius, surface tension, and vapour pressure or solubility of spherical particles is the same as that deduced in Chap. I, 15, for small drops. 

Ratsuta, H. Ishigai, T. Furukuwa, K. "Equilibrium Pressure and Solubility of Hydrogen in Liquid Lithium" Nucl. Tech. 1977, 32. 

Reported vapor pressures and aqueous solubilities of diethyl phthalate at various pressures and solubilities... 

PaIRT versus the saturation concentration in water [A°(aq)] for 25°C. The volatile compounds (H < 10) are in the upper left, while those in the lower right (H > 100) are relatively involatile. It is interesting to note that a homologous series of chemicals tend to lie at a line of constant H. Substituting methyl groups or chlorines for hydrogen tends to reduce both vapor pressure and solubility, by a factor of 4-6. Thus or H tends to remain relatively constant (Mackay, 1991). The H value for water in Figure 5.15 can be deduced... 

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