Solubility and Saturation

The solubility of a compoimd is defined as the amount of the compound, usually in grams, that dissolves in a certain amount of liquid. For example, the solubility of sodium chloride in water at 25 °C is 36 g NaCl per 100 g water, while the solubility 

Supersaturated solutions oan form under special circumstances, such as the sudden release in pressure that occurs in a soda can when it is opened. 

NaCI forms a strong electrolyte solution (Section 7.5). Weak electrolyte solutions are covered in Chapter 14. 

Electrolyte solutions contain dissolved ions (charged particles) and therefore conduct electricity. Nonelectrolyte solutions contain dissolved molecules (neutral particles) and so do not conduct electricity. 

Chapter 7 introduced the solubility rules (Section 7.5, Table 7.2), which give us a qualitative description of the solubility of ionic solids. Molecular solids may also be soluble in water depending on whether the solid is polar. Table sugar (C12H22O11), for example, is polar and soluble in water. Nonpolar solids, such as lard and vegetable shortening, are usually insoluble in water. 

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Figure 7.2. Solubility and saturation. A schematic solubility diagram showing concentration ranges versus pH for supersaturated, metastable, saturated, and undersaturated solutions. A supersaturated solution in the labile concentration range forms a precipitate spontaneously a metastable solution may form no precipitate over a relatively long period. Often an active form of the precipitate, usually a very fine crystalline solid phase with a disordered lattice, is formed from oversaturated solutions. Such an active precipitate may persist in metastable equilibrium with the solution it is more soluble than the stable solid phase and may slowly convert into the stable phase.

Box 4.12 Solubility product, mineral solubility and saturation index... 

INFLUENCES ON THE SOLUBILITY AND SATURATION STATE OF CARBONATE MINERALS... 

Sec. 6.4 Influences on the Solubility and Saturation State of Carbonate Minerals... 

Solubilities of ionic salts Solubility and saturated solutions... 

An alternative method for isolating the n-butyl ether utilises the fact that n-butyl alcohol is soluble in saturated calcium chloride solution whilst n-butyl ether is slightly soluble. Cool the reaction mixture in ice and transfer to a separatory fimnel. Wash cautiously with 100 ml. of 2-5-3N sodium hydroxide solution the washings should be alkaline to litmus. Then wash with 30 ml. of water, followed by 30 ml. of saturated calcium chloride solution. Dry with 2-3 g. of anhydrous calcium chloride, filter and distil. Collect the di-n-butyl ether at 139-142°. The yield is 20 g. 

The physical properties of vinyl chloride are Hsted in Table 1 (12). Vinyl chloride and water [7732-18-5] are nearly immiscible. The equiUbrium concentration of vinyl chloride at 1 atm partial pressure in water is 0.276 wt % at 25°C, whereas the solubiUty of water in vinyl chloride is 0.0983 wt % at 25°C and saturated pressure (13). Vinyl chloride is soluble in hydrocarbons, oil, alcohol, chlorinated solvents, and most common organic Hquids. 

Cyclosporin A forms white prismatic crystals from acetone and is only slightly soluble in water and saturated hydrocarbons, but is very soluble in methanol, ethanol, acetone, and diethyl ether. Optical and nmr data on cyclosporins and x-ray crystallographic data on cyclosporin A and an io do derivative have been reviewed (273,275). 

The beneficial effects of dietary fiber, including both soluble and iasoluble fiber, are generally recognized. Current recommendations are for daily iatakes of 20—35 g ia a balanced diet of cereal products, fmits, vegetables, and legumes. However, the specific preventive role of dietary fiber ia certaia diseases has beea difficult to estabUsh, ia part because dietary risk factors such as high saturated fat and high proteia levels are reduced as fiber levels iacrease. 

Quicklime, CaO, has a density range of approximately 55 to 75 Ib/cu ft, and a molecular weight of 56.08. A slurry for feeding, called milk of lime, can be prepared with up to 45 percent solids. Lime is only slightly soluble, and both lime dust and slurries are caustic in nature. A saturated solution of lime has a pH of about 12.4. 

The toxic effect depends both on lipid and blood solubility. I his will be illustrated with an example of anesthetic gases. The solubility of dinitrous oxide (N2O) in blood is very small therefore, it very quickly saturates in the blood, and its effect on the central nervous system is quick, but because N,0 is not highly lipid soluble, it does not cause deep anesthesia. Halothane and diethyl ether, in contrast, are very lipid soluble, and their solubility in the blood is also high. Thus, their saturation in the blood takes place slowly. For the same reason, the increase of tissue concentration is a slow process. On the other hand, the depression of the central nervous system may become deep, and may even cause death. During the elimination phase, the same processes occur in reverse order. N2O is rapidly eliminated whereas the elimination of halothane and diethyl ether is slow. In addition, only a small part of halothane and diethyl ether are eliminated via the lungs. They require first biotransformation and then elimination of the metabolites through the kidneys into the... 

The term solubility thus denotes the extent to which different substances, in whatever state of aggregation, are miscible in each other. The constituent of the resulting solution present in large excess is known as the solvent, the other constituent being the solute. The power of a solvent is usually expressed as the mass of solute that can be dissolved in a given mass of pure solvent at one specified temperature. The solution s temperature coefficient of solubility is another important factor and determines the crystal yield if the coefficient is positive then an increase in temperature will increase solute solubility and so solution saturation. An ideal solution is one in which interactions between solute and solvent molecules are identical with that between the solute molecules and the solvent molecules themselves. A truly ideal solution, however, is unlikely to exist so the concept is only used as a reference condition. 

The most common backbone structure found in commercial polymers is the saturated carbon-carbon structure. Polymers with saturated carbon-carbon backbones, such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyacrylates, are produced using chain-growth polymerizations. The saturated carbon-carbon backbone of polyethylene with no side groups is a relatively flexible polymer chain. The glass transition temperature is low at -20°C for high-density polyethylene. Side groups on the carbon-carbon backbone influence thermal transitions, solubility, and other polymer properties. 

The isomerisation of aUylic alcohols to saturated ketones usually has a strong thermodynamic driving force. The ruthenium NHC complex 62 has been used to catalyse the isomerisation of allylic alcohol 59 which gives ketone 60 as the principal product along with some of the reduction product 61 [32]. The catalyst was water-soluble and the aqueous phase could be re-used for several runs (Scheme 11.15). NHC analogues of Crabtree s catalyst, [IrlPCyjKpyridineXcod)] PFg, were found to be less efficient for the isomerisation of allylic alcohols than... 

The basic relationships between solubility and pH can be derived for any given equilibrium model. The model refers to a set of equilibrium equations and the associated equilibrium quotients. In a saturated solution, three additional equations need to be considered, along with the ionization Eqs. (2a)-(2d), which describe the equilibria between the dissolved acid, base or ampholyte in solutions containing a suspension of the (usually crystaUine) solid form of the compounds ... 

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