Sparingly soluble compounds

In the presence of mineral phases containing anions that would form sparingly soluble compounds (e.g. POt - and F for the lower oxidation states) an enhanced plutonium uptake due to chemisorption can be expected (57). For plutonium in the higher oxidation states the formation of anionic carbonate complexes would drastically reduce the sorption on e.g oxide and silicate surfaces. 

Complex formation removes some of the Ag+ ions from solution. As a result, to preserve the value of Ksp, more silver chloride dissolves. Formation of a complex increases the solubility of a sparingly soluble compound. 

Use the data in Table 11.4 to calculate the solubility of each of the following sparingly soluble compounds in its respective solution iron(III) hydroxide at (a) pH = 11.0 ... 

Since most drug discovery projects deal with very sparingly soluble compounds, the usual CE sample concentration would lead to precipitation. The handling of real dmg candidate molecules is poorly developed in CE applications, in comparison to the most robust potentiometric method. 

C Nystrom, J Mazur, MI Barnett, M Glazer. Dissolution rate measurements of sparingly soluble compounds with the Coulter counter model TAIL J Pharm Pharmacol 37 217-221, 1985. 

All of the chemical species, except one, will be assumed to be completely soluble. The one partially insoluble species will nucleate and grow a solid phase. A typical example is A + B ->P where P is a sparingly soluble compound. The rates of nucleation J and molecular surface growth G can be functions of the local concentration vector c, the particle size l, and the local turbulence properties. Neglecting aggregation and breakage processes, a microscopic PBE for this system can be written as follows ... 

When a reagent is added to an analyte solution forming a sparingly soluble compound, the solubility product for that compound is immediately exceeded and the solution is said to be supersaturated. The relative supersaturation Rs is given by... 

Prepare treatment medium containing various concentrations of test compound 19.7 ml of Eagle s medium (without serum) plus 300 pi of stock concentration of compound in a preferred solvent (e.g., water, ethanol, DMSO, etc.). The final concentration of solvent other than water should not exceed 1% v/v. Normally a range of 0-5000 pg ml-1 (final concentration) is covered. For a sparingly soluble compound, the highest concentration will be the lowest at which visible precipitation occurs. Similarly, if a compound has a marked effect on osmolality, concentrations should not be used that exceed 500 milliosmoles (mosm) per kg. In addition, a pH range of 6.5-7.5 should be maintained. 

The nitrosophenol is precipitated from the cooled aqueous solution by acidification with dilute sulphuric acid and is extracted with ether in a separating funnel. After brief drying over calcium chloride the brownish-green solution is concentrated on the water bath. The sparingly soluble compound crystallises from the ether on cooling. Melting point 120°-130° (decomp.). Complete purification of nitrosophenol is difficult. 

Abnormally low Kow values have been obtained with sparingly soluble compounds, presumably because they do not achieve true equilibrium during the separation... 

You can use the relationship between the ion product expression and the solubility product expression to predict whether a precipitate will form in a given system. One common system involves mixing solutions of two soluble ionic compounds, which react to form an ionic compound with a very low solubility. If Qsp > Kp. based on the initial concentrations of the ions in solution, the sparingly soluble compound will form a precipitate. 

Thus, the electrode potential of an electrode of the t5q)e M MA A depends on the activity of anion of the sparingly soluble compound of the electrode metal. 

Mercury-Mercurous Sulfate Electrode. In this reference electrode the metal is mercury, the sparingly soluble compound is mercurous sulfate (Hg2S04), and the source of S04 anions is sulfuric acid or potassium sulfate. The electrode is made in the same way as a calomel electrode, and it is represented as... 

When sparingly soluble compounds have to be reduced they may be transported into the reaction flask for reduction by extraction in a Soxhlet apparatus surmounting the flask [[Pg.21]

Numerous techniques measuring properties such as conductance [27-29], surface tension [30-35] and solubilization of a sparingly soluble compound [36-40], and NMR [41-43] have been employed along with calorimetric... 

The value of this standard potential is slightly modified depending on the solid oxide structure and reaches —0.857 V for the quartz structure. In most acidic or neutral solutions, this silicon oxide forms a protecting layer. However, when the solution pH is increased, the oxide will give rise to various sparingly soluble compounds due to the following dissociahon reactions ... 

Since the rate of these processes can be carefully controlled, it is possible to establish conditions that would result in uniform particles by precipitation of sparingly soluble compounds, the composition of which is affected by cations and anions... 

The basis of these methods is the linear dependence of the absorbance of a solution on the concentration of the various absorbing solutes (Beer s law). Therefore, fundamental requisites are the adherence of the solutes to Beer s law and the constant absorptivity of each one of these species with changing solvent composition. When these requirements are met, the experimentally determined ratio of the concentrations of the ionized to the neutral species (say Q-/Cah) at different pH values leads to thermodynamic pKs (after the appropriate corrections for ionic strength effects). These methods are particularly valuable for the study of sparingly soluble compounds. 

K is the overall mass-transfer coefficient based on the liquid phase. A is the total interfacial area in the gas-liquid dispersion. C is the concentration in the liquid phase. C thus corresponds to equilibrium with the gas phase of composition y. H is the Henry coefficient for the gas. In the case of oxygen or a sparingly soluble compound, H is large and resistance to mass transfer is located in the liquid phase. 

Determine the Ksp for the following sparingly soluble compounds, given their molar solubilities ... 

Use the data in Table 11.5 to calculate the solubility of each sparingly soluble compound... 

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