Solute-dependent

It has long been known that the form of a curved surface of mercury in contact with an electrolyte solution depends on its state of electrification [108, 109], and the earliest comprehensive investigation of the electrocapillary effect was made by Lippmann in 1875 [110]. A sketch of his apparatus is shown in Fig. V-10. 

The conductivity of solutions depends, from A2.4.31. on both the concentration of ions and their mobility. Typically, for 1 M NaCl in water at 18°C, a value of 7.44 is found by contrast, 1 M H2SO4 has a... 

Accepting, for the moment without further evidence, that the nitro-nium ion formed by heterolysis of nitric acid is the active reagent in the solutions imder discussion, it remains to consider briefly why nitration in such solutions depends on the concentrations of nitric acid to such high powers (fig. 3.1), and why different solvents behave so differently (table 3.2). 

It IS not possible to tell by inspection whether the a or p pyranose form of a par ticular carbohydrate predominates at equilibrium As just described the p pyranose form IS the major species present m an aqueous solution of d glucose whereas the a pyranose form predominates m a solution of d mannose (Problem 25 8) The relative abundance of a and p pyranose forms m solution depends on two factors The first is solvation of the anomeric hydroxyl group An equatorial OH is less crowded and better solvated by water than an axial one This effect stabilizes the p pyranose form m aqueous solution The other factor called the anomeric effect, involves an electronic interaction between the nng oxygen and the anomeric substituent and preferentially stabilizes the axial OH of the a pyranose form Because the two effects operate m different directions but are com parable m magnitude m aqueous solution the a pyranose form is more abundant for some carbohydrates and the p pyranose form for others... 

The true thermodynamic equilibrium constant is a function of activity rather than concentration. The activity of a species, a, is defined as the product of its molar concentration, [A], and a solution-dependent activity coefficient, Ya. 

Source Compiled from Rechnitz, G. A. Controlled-Potential Analysis. Macmillan New York, 1963, p. 49. Electrolytic reactions are written in terms of the change in oxidation state. The actual species in solution depend on the composition of the sample matrix. 

The efficiency of separation of solvent from solute varies with their nature and the rate of flow of liquid from the HPLC into the interface. Volatile solvents like hexane can be evaporated quickly and tend not to form large clusters, and therefore rates of flow of about 1 ml/min can be accepted from the HPLC apparatus. For less-volatile solvents like water, evaporation is slower, clusters are less easily broken down, and maximum flow rates are about 0.1-0.5 ml/min. Because separation of solvent from solute depends on relative volatilities and rates of diffusion, the greater the molecular mass difference between them, the better is the efficiency of separation. Generally, HPLC is used for substances that are nonvolatile or are thermally labile, as they would otherwise be analyzed by the practically simpler GC method the nonvolatile substances usually have molecular masses considerably larger than those of commonly used HPLC solvents, so separation is good. 

The flow properties of sodium alginate solutions depend on concentration. A 2.5% medium viscosity sodium alginate solution is pseudoplastic, especially at the higher shear rates in the range of 10—10,000/s. 

In aqueous solution, all the sodium peroxoborates dissociate for the most part into boric acid, or its anion, and hydrogen peroxide. Peroxoborate species are also present in these solutions, depending on the pH and the concentration for the species type. The nature of these species has been extensively examined by classical physicochemical methods (13), by nmr, and by Raman spectroscopy (14—17). Both monomeric and polymeric species are usually present. There is some evidence (18) suggesting that these peroxoborates are more reactive than hydrogen peroxide alone under similar conditions. 

Amine oxides show either nonionic or cationic behavior in aqueous solution depending on pH. In acid solution the cationic form (R2N" OH) is observed (2) while in neutral and alkaline solution the nonionic form predorninates as the hydrate R NO H2O. The formation of an ionic species in the acidic pH range stabilizes the form generated by the most studied commercial amine oxide, dimethyldodecylamine oxide (6). 

In this reaction sequence, equation 47, the formation of the complex ion, Zn(OH)3, is the rate determining step. Once the solubiUty of 2incate, Zn(OH), is exceeded, 2inc hydroxide [20427-58-17, Zn(OH)2, precipitates. The crystal form that falls out of solution depends on the concentration of the alkah. 

The standard reduction potential of Cr " (Table 2) shows that this ion is a strong reducing agent, and Cr(II) compounds have been used as reagents in analytical chemistry procedures (26). The reduction potential also explains why Cr(II) compounds are unstable in aqueous solutions. In the presence of air, the oxidation to Cr(III) occurs by reaction with oxygen. However, Cr(II) also reacts with water in deoxygenated solutions, depending on acidity and the anion present, to produce H2 and Cr(III) (27,28). 

The properties of copper(Il) are quite different. Ligands that form strong coordinate bonds bind copper(Il) readily to form complexes in which the copper has coordination numbers of 4 or 6, such as tetraammine copper(Tl) [16828-95-8] [Cu(NH3)4], and hexaaquacopper(Il) [14946-74-8] [Cu(H,0),p+ ( see Coordination compounds). Formation of copper(Il) complexes in aqueous solution depends on the abiUty of the ligands to compete with water for coordination sites. Most copper(Il) complexes are colored and paramagnetic as a result of the unpaired electron in the 2d orbital (see Copper... 

A numerical solution of this equation for a constant surface concentration (infinite fluid volume) is given by Garg and Ruthven [Chem. Eng. ScL, 27, 417 (1972)]. The solution depends on the value of A. = n i — n )/ n — n ). Because of the effect of adsorbate concentration on the effective diffusivity, for large concentration steps adsorption is faster than desorption, while for small concentration steps, when D, can be taken to he essentially constant, adsorption and desorption curves are mirror images of each other as predicted by Eq. (16-96) see Ruthven, gen. refs., p. 175. 

The puff model describes near-instantaneous releases of material. The solution depends on the total quantity of material released, the atmospheric conditions, the height of the release above ground, and the distance from the release. The equation for the average concentration for this case is (Growl and Louvar, 1990, p, 143) ... 

EA Carter, JT Elynes. Solute-dependent solvent force constants for ion pairs and neutral pairs m a polar solvent. J Phys Chem 93 2184-2187, 1989. 

Fig. 4.18. Detection limit ofTXRF for the residues of aqueous solutions, depending on the atomic number of the analyte element. Three excitations modes were used (a) W-tube, 50 kV Ni-fil-ter, cutoff 35 keV (b) Mo-tube 50 kV Mo filter, cutoff 20 keV (c) W-tube,...

At the end of the 1930s, the only generally available method for determining mean MWs of polymers was by chemical analysis of the concentration of chain end-groups this was not very accurate and not applicable to all polymers. The difficulty of applying well tried physical chemical methods to this problem has been well put in a reminiscence of early days in polymer science by Stockmayer and Zimm (1984). The determination of MWs of a solute in dilute solution depends on the ideal, Raoult s Law term (which diminishes as the reciprocal of the MW), but to eliminate the non-ideal terms which can be substantial for polymers and which are independent of MW, one has to go to ever lower concentrations, and eventually one runs out of measurement accuracy . The methods which were introduced in the 1940s and 1950s are analysed in Chapter 11 of Morawetz s book. 

The facility with which a-cleavage occurs in solution depends on the stability of ttae adical fragments that can be ejected. Dibenzyl ketone, for exan le, is readify cleav jjiboto-lytically. Similarly, r-butyl ketones undergo a-cleavage quite readify on p ioCo in solution. ... 

TLC measurements used for the identification of unknown solutes depends on two basic pai ameters. Firstly, the distance traveled by the solvent front, measured from the sampling point or sampling boundary, and secondly, on the distance traveled by the spot from the sampling point or sampling boundary. These are the sole... 

The accuracy of a CFD program is greatly influenced by the number of cells in the grid. The larger the number of cells, the more accurate the solution. Additionally, the cost of computer hardware and calculation time combined with the accuracy of a solution depends on the preciseness of the grid. 

The restrictions on engineering constants can also be used in the solution of practical engineering analysis problems. For example, consider a differential equation that has several solutions depending on the relative values of the coefficients in the differential equation. Those coefficients in a physical problem of deformation of a body involve the elastic constants. The restrictions on elastic constants can then be used to determine which solution to the differential equation is applicable. 

The solubility of AS2O3 in water, and the species present in solution, depend markedly on pH. In pure water at 25°C the solubility is 2.16 g per lOOg this diminishes in dilute HCl to a minimum of 1.56g per lOOg at about 3 m HCl and then increases, presumably due to the formation of chloro-complexes. In neutral or acid solutions the main species is probably pyramidal As(OH)3, arsenious acid , though this compound has never been isolated either from solution or otherwise (cf. carbonic acid, p. 310). The solubility is much greater in basic solutions and spectroscopic evidence points to... 

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