Solutions aqueous, concentrative properties

Physical Properties. Pure, anhydrous lactic acid is a white, crystalline soHd with a low melting poiat. However, it is difficult to prepare the pure anhydrous form of lactic acid generally, it is available as a dilute or concentrated aqueous solution. The properties of lactic acid and its derivatives have been reviewed (6). A few important physical and thermodynamic properties from this reference are summarized ia Table 1. 

An important property of the protein metal complexes is that their solubilities are particularly influenced by the dielectric constant of the medium. Thus, a moderate reduction of the dielectric constant of an aqueous solution will precipitate the Ba or Zn salts of many proteins which are readily soluble in the aqueous solutions. This property has been used for the fractionation of the plasma proteins. The use of barium and zinc salts not only gave superior fractionation, but also allowed the use of lower ethanol concentrations with diminished risk of denaturation. 

Emulsion concentrates (ECs) are one of the oldest formulation types for agricultural pesticides. Even today, ECs are a prevalent delivery system. As liquid formulations, with physical properties similar to the aqueous solution concentrates, these formulations are easy to use, transport, and mix. 

The oxidising properties of the aqueous solutions of chloric(VII) acid change dramatically with temperature and the concentration of the acid. Cold dilute solutions have very weak oxidising properties and these solutions will react, for example, with metals, producing hydrogen without reduction of the chlorate(VII) ion occurring ... 

Properties. Fluoroboric acid is stable in concentrated solutions, and hydroly2es slowly in aqueous solution to hydroxyduoroborates. For the stabihty of the duoroborate species, see Reference 3. The equiUbrium quotients (4,5) in 1 molal NaCl at 25°C show the strong affinity of boron for duo ride ... 

Mahc acid is a relatively strong acid. Its dissociation constants are given in Table 1. The pH of a 0.001% aqueous solution is 3.80, that of 0.1% solution is 2.80, and that of a 1.0% solution is 2.34. Many of its physical properties are similar to those of citric acid (qv). Solubihty characteristics are shown in Figure 1 and Table 1, densities of aqueous solutions are hsted in Table 2, and pH values vs concentration are shown in Figure 2. 

Physical Properties. When crystaUized from aqueous solutions above 5°C, natural (R-R, R )-tartaric acid is obtained in the anhydrous form. Below 5°C, tartaric acid forms a monohydrate which is unstable at room temperature. The optical rotation of an aqueous solution varies with concentration. It is stable in air and racemizes with great ease on heating. Some of the physical properties of (R-R, R )-tartaric acid are Hsted in Table 7. 

Liquid Crystalline Structures. In certain ceUular organeUes, deoxyribonucleic acid (DNA) occurs in a concentrated form. Striking similarities between the optical properties derived from the underlying supramolecular organization of the concentrated DNA phases and those observed in chiral nematic textures have been described (36). Concentrated aqueous solutions of nucleic acids exhibit a chiral nematic texture in vitro (29,37). 

Films or membranes of silkworm silk have been produced by air-drying aqueous solutions prepared from the concentrated salts, followed by dialysis (11,28). The films, which are water soluble, generally contain silk in the silk I conformation with a significant content of random coil. Many different treatments have been used to modify these films to decrease their water solubiUty by converting silk I to silk II in a process found usehil for enzyme entrapment (28). Silk membranes have also been cast from fibroin solutions and characterized for permeation properties. Oxygen and water vapor transmission rates were dependent on the exposure conditions to methanol to faciUtate the conversion to silk II (29). Thin monolayer films have been formed from solubilized silkworm silk using Langmuir techniques to faciUtate stmctural characterization of the protein (30). ResolubiLized silkworm cocoon silk has been spun into fibers (31), as have recombinant silkworm silks (32). 

The specific rotation ia water is [0 ] ° — +66.529° (26 g pure sucrose made to 100 cm with water). This property is the basis for measurement of sucrose concentration ia aqueous solution by polarimetry. 100°Z iadicates 100% sucrose on soHds. 

Abbreviations of prominent use properties of the various classes of commercial surfactants are shown in Table 1. Antimicrobial activity includes germicidal, bactericidal, and bacteriostatic effects emolliency describes lubrication or a soft feel imparted to skin by surfactants a hair conditioner is a substantive surfactant appHed from aqueous solution to impart a lubricating or antistatic effect and opacifters are used to thicken hand-dishwashing products and cosmetic preparations to convey an appearance of high concentration and to retard solvent drainage from foam. 

Micellar properties are affected by changes in the environment, eg, temperature, solvents, electrolytes, and solubilized components. These changes include compHcated phase changes, viscosity effects, gel formation, and Hquefication of Hquid crystals. Of the simpler changes, high concentrations of water-soluble alcohols in aqueous solution often dissolve micelles and in nonaqueous solvents addition of water frequendy causes a sharp increase in micellar size. 

Properties. Thienamycin is isolated as a colorless, hygroscopic, zwitterionic soHd, although the majority of carbapenems have been obtained as sodium salts and, in the case of the sulfated olivanic acids, as disodium salts (12). Concentrated aqueous solutions of the carbapenems are generally unstable, particularly at low pH. AH the substituted natural products have characteristic uv absorption properties that are often used in assay procedures. The ir frequency of the P-lactam carbonyl is in the range 1760 1790 cm . ... 

Dichloramine. The least stable chloramine, dichloramine [3400-09-7] has not been prepared in pure form. However, it has sufficient stabiUty in dilute organic or aqueous solutions for deterrnination of some physical and chemical properties. It has a pungent odor and can impart an odor or off-taste to water at concentrations above 0.8 ppm. Dichloramine can be produced by reaction of HOCl with a slight excess of NH in the pH range 4—7 or by disproportionation of NH2CI at pH 3.5—4.0 ... 

II The increment in the free energy, AF, in the reaction of forming the given substance in its standard state from its elements in their standard states. The standard states are for a gas, fugacity (approximately equal to the pressure) of 1 atm for a pure liquid or solid, the substance at a pressure of 1 atm for a substance in aqueous solution, the hyj)othetical solution of unit molahty, which has all the properties of the infinitely dilute solution except the property of concentration. 

In this study we examined the influence of concentration conditions, acidity of solutions, and electrolytes inclusions on the liophilic properties of the surfactant-rich phases of polyethoxylated alkylphenols OP-7 and OP-10 at the cloud point temperature. The liophilic properties of micellar phases formed under different conditions were determined by the estimation of effective hydration values and solvatation free energy of methylene and carboxyl groups at cloud-point extraction of aliphatic acids. It was demonstrated that micellar phases formed from the low concentrated aqueous solutions of the surfactant have more hydrophobic properties than the phases resulting from highly concentrated solutions. The influence of media acidity on the liophilic properties of the surfactant phases was also exposed. 

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