Maximum solubility

EXAFS studies on tris-maltolatoiron(III) in the solid state and in solution, and on [Fe(Ll)3] hydrate, pave the way for detailed investigation of the hydration of complexes of this type in aqueous media.Solubilities and transfer chemical potentials have been determined for tris-maltolatoiron(III) in methanol-water, and for tris-etiwlmaltolatoiron(III) in alcohol-water mixtures and in isobutanol, 1-hexanol, and 1-octanol. Solubility maxima in mixed solvents, indicating synergic solvation, is relevant to trans-membrane transport of complexes of this type. Solubilities of tris-ethylmaltolatoiron(III) and of [Fe(Ll)3] have been determined in aqueous salt solutions (alkali halides NH4 and NR4 bromides). ... 

The solubility of sulphamethoxypyridazine in ethanol-water mixtures represents a rare kind of drug solubility in an aqueous mixed solvent, because it exhibits two solubility maxima on the curve solubility versus mixed solvent composition (Escalera et al., 1994). It is of interest to verify if such behavior satisfies the thermodynamic consistency criterion. The values of D were calculated using Eq. (11), and... 

Escalera, J.B., Bustamante, P, Martin, A., 1994. Predicting the solubility of drugs in solvent mixtures - multiple solubility maxima and the chameleonic effect. J. Pharm. Pharmacol. 46, 172-176. 

The solubility parameters of insoluble polymers are often determined by swelling the polymer in a series of solvents with different solubility parameter values. Maximum swelling of the polymer then occurs in those solvents whose solubility parameters are closest to that of the polymer. It is interesting to note that swelling data for Nafion, when interpreted in this way. Indicate the presence of two solubility maxima that is, this ionomeric polymer acts as if it had two different solubility parameters (21). This seems reasonable for a polymer that is composed of two different phases neither solubility maximum, however, is very close to the solubility parameter of water. 

Aqueous solubility is governed by the counteracting effects of the AS of dissolution versus the AH of chemical bonding in solids. The AH of Na+ compounds tends to be small. Therefore, AS prevails and Na+ remains in solution The AH values of AI and Si bonds with O2- and OH-, on the other hand, are large, s-o the aqueous solubility of those compounds is low, and the Al3+ and Si(OH)4 concentrations soon reach their solubility maxima in water. Soil solution conditions are often such that Al3+ and Si(OH)4 precipitate as kaolinite... 

Furthermore, COSMO-RS is known to perform well for predictions of activity coefficients and solubilities in solvent mixtures [14,23] and in most cases reproduces solubility maxima correctly. A challenging problem case, however, the solubility of paracetamol in a water-dioxane mixture, is shown in Figure 9.3. Experimental data for the system paracetamol/water-dioxane have been taken from three different sources [31-33] and compared with COSMOt/term computations at the TZVP and the newer FINE parameterization [6]. 

Solute Miscibility Region Fractionation Range for the Solutes Solute Solubility Maxima Solute Physical Properties... 

The marked temperature dependence of borate solubility may be useful in certain oilfield chemical applications. It is also notable that water solubility varies with the ratio of min (the compound s molar content of M2O/B2O3) with solubility maxima corresponding approximately with the compounds disodium octaborate (min = 0.25) and sodium metaborate (min = 1.0) and with a minimum that corresponds with disodium tetraborate (borax) (m n = 0.5) [13,14]. 

It has been shown that this equation of state is able to give a good correlation in the overall pressure range, whereas the Redlich-Kwong equation of state, as reported earlier [21,40,41], cannot represent solubility maxima. 

Solubilities of quartz and amorphous silica in aqueous solutions increase with increasing of temperature (Holland and Malinin, 1979). Solubility of barite depends on salinity and temperature (Blount, 1977). The solubility of barite in hydrothermal solution having more than 1 molal NaCl concentration increases with increasing temperature, while a solubility maximum exists in the solution with NaCl concentration less than ca. 0.2 molal (Blount, 1977). 

Table II gives the temperature interval, the number of laboratories that Battino judges have published reliable solubility data, the number of experimental values used in the linear regression, the linear regression standard deviation at the midpoint temperature, and the temperature of minimum mole fraction solubility (maximum value of Henry s constant) at one atmosphere partial pressure of the gas. For all of the gases except oxygen only a three constant equation was used.

Water Solubility—Maximum concentration of a substance that will dissolve in water. 

The extensions of the Hildebrand and Hansen approaches are both empirical. Afterthe solubility behavior has been evaluated in a series of solvent systems, regression analysis can be used to estimate the empirical coefLcients, including th fferm of the extended Hansen approach, and then the solubility can be estimated in a solvent system which has not been included in the experimental portion of the study. The problem with acknowledging the predictive power of these equations is that the solubility in many solvents must be determined before being able to predict the solubility in the solvent of choice. It is probably easier to simply perform the solubility study in the solvent of choice and eliminate the prediction equation altogether. On the other hand, in a study of binary solvent systems consisting of water and a cosolvent appropriate to parenteral products, the solubility maximum in that series can be readily estimated by the mathematical expression Lnally achieved. 

It is essential to realize that any thermodynamic evaluation of this solubility "maximum" with standard reference conditions in the form of the three pure components in liquid form is a futile exercise. The complete phase diagram. Fig. 2, shows the "maximum" of the solubility area to mark only a change in the structure of the phase in equilibrium with the solubility region. The maximum of the solubility is a reflection of the fact that the water as equilibrium body is replaced by a lamellar liquid crystalline phase. Since this phase.transition obviously is more. related to packing constraints — than enthalpy of formation — a view of the different phases as one continuous region such as in the short chain compounds water/ethanol/ethyl acetate. Fig. 3, is realistic. The three phases in the complete diagram. Fig. 2, may be perceived as a continuous solubility area with different packing conditions in different parts (Fig. 4). 

Sweetening power as compared to a 10% sucrose solution in water ADI value acceptable daily intake in mg per kg of body weight (bw) per day US limit maximum amount permitted in soft drinks in the USA EU limit maximum amount permitted in soft drinks in the EU solubility maximum solubility of the raw material in water. 

The experimental fact that the sodium hydroxide concentration at the solubility maximum is usually over 30% indicates that highly concentrated (usually 45-50%) NaOH is required for the preparation of most alkali hydroxo salts. This is also necessary to ensure good yields. However, most alkaline earth hydroxometalates can be prepared from more dilute NaOH solutions. 

In the case of lead pipes, simple oxidative corrosion of the metal forms a coating of lead carbonate on the inside wall of the pipe. As shown in theoretical and empirical studies, the lead solubility (maximum lead concentration) is a function of water characteristics, mainly pH, alkalinity and temperature, as well as, eventually, orthophosphate concentration (Sheiham and Jackson, 1981 Kuch and Wagner, 1983 Van den Hoven, 1986 Schock, 1989,1990,1994 Wagner, 1992 Leroy, 1993). Fora given alkalinity, lead solubility decreases when pH increases. Theoretical lead solubility varies between several mg/1 for very soft waters with low pH (alkalinity < 30 mg/1 CaCOs and pH < 6.5) to less than 100 pg/1 in waters with alkalinity between 50 and 150 mg/1 CaCOs and pH above 8. 

These observations point to the complex nature of the phase behavior of these systems and possible solubility maximum for the polymer in the binary fluid system consisting of monomer plus carbon dioxide. 

As pointed out in the previous section, molecular weight maximum with pressure has been noted in some other systems, however the fluid mixture density information for those systems have not been reported to test if density plays a key role in those system also. The notion of solubility maximum has not been evaluated for the polymerization in the SF6 + CO2 mixtures. 

The solute and solvent atoms should have similar valences in order for maximum solubility, rather than compound formation. In general, a greater solubility will result from the dissolution of a higher-valence solute species in a lower-valence solvent lattice, than vice versa. For instance, the solubility limit of Zn in Cu is 38.4 at.% Zn, but only 2.3 at.% Cu for Cu in Zn. Solubilities also decrease with an increase in periodic separation for example, the solubility maximum is 38.4% Zn in Cu, 19.9% Ga in Cu, 11.8% Ge in Cu, and only 6.9% As in Cu. 

The normal melting temperature of phenanthrene is 96.3°C. Its enthalpy change of fusion is 18.6kJmol. Find the solubility (maximum mole fraction) of phenanthrene in a liquid solution with naphthalene at 82.0°C. Assume that the liquid solution is ideal and that no solid solubility occurs. 

Excellent UV. Limited solubility— maximum 45—50% CH3CN. Can combine dilute phos jiate with neutral salt such as NaCI... 

For all calculations reported here, binary parameters from VLE data were obtained using the principle of maximum likelihood as discussed in Chapter 6, Binary parameters for partially miscible pairs were obtained from mutual-solubility data alone. 

The maximum concentration atltainable under such conditions is termed the solubility of the substance at the specific temperature used in the experiment, since solubility generally increases with rising temperature. Solubility is usually expressed in grams per 100 g of solvent, or grams per 100 g of solution. Sometimes, for practical convenience, it may be expressed in grams per 100 ml of solvent or solution. 

When the temperature decreases, water becomes less soluble (see Figure 5.15) and deposits as fine droplets that begin to freeze as the temperature reaches 0°C. To prevent this occurrence, it is possible to use anti-freeze additives that absorb the water and lower the freezing point. These products, used at maximum levels of 1500 ppm, are ethers-alcohols for example, 2-methoxy... 

It should be noted that the modern view is that all partially miscible liquids should have both a lower and upper critical solution temperature so that all such systems really belong to one class. A closed solubility curve is not obtain in all cases because the physical conditions under normal pressure prevent this. Thus with liquids possessing a lower C.S.T., the critical temperature (the critical point for the liquid vapour system for each component, the maximum temperature at which liquefaction is possible) may be reached before the consolute temperature. Similarly for liquids with an upper C.S.T., one or both of the liquids may freeze before the lower C.S.T. is attained. 

The maximum permissible body burden for ingested polonium is only 0.03 microcuries, which represents a particle weighing only 6.8 x IO-12 g. Weight for weight it is about 2.5 x lOii times as toxic as hydrocyanic acid. The maximum allowable concentration for soluble polonium compounds in air is about 2 x lO-ii microcuries/cnu. 

Fig. 1. R,i (zt)-Malic acid solubility in water, showing maximum solubilities vs temperature (4).

The general sales specification under which maleic anhydride is sold ia the United States specifies a white fused mass or briquettes of 99.5% minimum assay and 52.5°C minimum crystallisation poiat. The melt color specification is 20 APHA maximum with a maximum APHA color of 40 after two hours of heating at 140°C. Four grams of maleic anhydride ia 10 milliliters of water are to be completely soluble. The resulting solution is to be colodess. The acidity resulting from maleic acid is allowed to be a maximum of 0.2%. 

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