Chemistry solution

In recent years, many studies have been devoted to the transition metal halides in aqueous solution by X-ray and neutron diffraction and by EXAFS The local environment of the metal ion differs greatly for the different elements and valence states. Thus, for the chloride solutions, Fe and Cu show an important bonding to CP whereas and Co exhibit little or no bonding. 

Sadoc et al. have studied the aqueous solution of CdBr by EXAFS measurements 

A similar study has been performed by Lagarde et al. on several strong II—I electrolytic solutions CuBr, CuCl. show very different local orders. 

In the case of CuBr and ZnBr concentrated solutions, the authors suggest a model built up with MBr tetrahedral units together in a solid like structure, ressembling that of the corresponding crystals. In the case of CuBr, these extended structures involve 50 % of the metal ions and 85 % in the case of ZnBr. The surrounding of the metal ion and of the bromine atom are given in Table 4. 

When the concentration decreases, the percentage of metal atoms involved in these structures decreases too but, even at low concentrations (0.1 M), there is still evidence of metal-halogen bonding. The local order in the CuCl solutions seems to be similar but it is rather difficult to obtain quantitative informations. 

Berkelium exhibits both the III and IV oxidation states, as would be expected from the oxidation states displayed by its lanthanide counterpart, terbium. Bk(III) is the most stable oxidation state in noncomplex-ing aqueous solution. Bk(IV) is reasonably stable in solution, undoubtedly because of the stabilizing influence of the half-filled Sf7 electronic configuration. Bk(III) and Bk(IV) exist in aqueous solution as the simple hydrated ions Bk3+(aq) and Bk4+(aq), respectively, unless com-plexed by ligands. Bk(III) is green in most mineral acid solutions. Bk(IV) is yellow in HC1 solution and is orange-yellow in H2S04 solution. A discussion of the absorption spectra of berkelium ions in solution can be found in Section IV,C. 

The possible existence of divalent berkelium was studied by polarog-raphy in acetonitrile solution. Because of high background currents (caused by radiolysis products) obscuring the polarographic wave, evidence for Bk(II) was not obtained (182). Divalent berkelium has been reported to exist in mixed lanthanide chloride-strontium chloride melts. The claim is based on the results of the distribution of trace 

Values of thermodynamic quantities for the formation of berkelium ions in solution, according to the reactions 

An electrostatic hydration model has been applied to the trivalent lanthanide and actinide ions in order to predict the standard free energy (AG°) and enthalpy (AHt) of hydration for these series. Assuming crystallographic and gas-phase radii for Bk(III) to be 0.096 and 0.1534 nm, respectively, and using 6.1 as the primary hydration number, AG298 was calculated to be -3357 kJ/mol, and A/Z298 was calculated to be -3503 kJ/mol (187). 

Activity coefficients for Bk(III) in aqueous NaNC 3 solutions have been calculated from distribution data for the ion between the aqueous phase and a tertiary alkylamine organic phase (188). The activity coefficient values were reported as a function of the NaNC 3 concentration. 

Very little new data based on experimental work has appeared since the I.A.E.A. publication on the aqueous actinide ions (3a,b). The current situation has been reviewed in refs. 4b, 8c). 

An earlier analysis of the crystallographic data suggested an ionic radius for of 102.5 pm in a 6-coordinate environment 4a). A more recent examination of all the available data gave 102.8 and 116 pm in 

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6- and 8-coordination, respectively (4b). An estimate for of 108 and 122 pm, for the same coordination numbers, was also made (46). 

There is not much information on the hydration of these trivalent cations. Estimates made on the basis of the calculated entropies of hydration suggest a hydration number of about 7 (5, 6a). But an estimate made by extrapolation of data for electrophoretic transport measurements on the ions of some heavier actinides indicate a hydration number of about 12.7, with nine water molecules in the first coordination sphere (66), 

Campbell, Dean J. Lorenz, Julie K. Ellis, Arthur B. Kuech, Thomas F. Lisensky, George Whittingham, C. and Stanley, M. (1998). The Computer as a Materials Science Benchmark. of Chemical Education 75 297-312. 

Arthur B. Geselbracht, MargretJ. Johnson, Brian J. Lisensky, George C. and Robinson, William R. (1993). Teaching General Chemistry A Materials Science Companion. Washington, DC American Chemical Society. 

Marshall. How Semiconductors Work. HowStuffWorks, Inc. Available from http //www.howstuffworks.com/diode.htm . 

The majority of chemical processes are reactions that occtu- in solution. Important industrial processes often utilize solution chemistry. Life is the sum of a series of complex processes occurring in solution. Air, tap water, tincture of iodine, beverages, and household ammonia are common examples of solutions. 

A solution is a homogenous mixture of substances with variable composition. The substance present in the major proportion is called the solvent, whereas the substance present in the minor proportion is called the solute. It is possible to have solutions composed of several solutes. The process of a solute dissolving in a solute is called dissolution. 

The chemical reagents involved in the preparation of the sol have a strong effect on the film characteristics and the electrical properties. Many examples can be found in the literature [16,19-22,30,41-43,47-51]. 

V is the formal valence of the complex, Vr is its residual valence when the formation of hydrogen bonds is taken into account, N is the number of external bonds the oxygen atoms are expected to form, and 5b is the Lewis base strength of the complex ion 

Strongly attached to give Fe(H20)6(H20) with 9, a number that gives a bonding strength equal to that of water. 

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The kinetics of crystal growth has been much studied Refs. 98-102 are representative. Often there is a time lag before crystallization starts, whose parametric dependence may be indicative of the nucleation mechanism. The crystal growth that follows may be controlled by diffusion or by surface or solution chemistry (see also Section XVI-2C). 

This interface is critically important in many applications, as well as in biological systems. For example, the movement of pollutants tln-ough the enviromnent involves a series of chemical reactions of aqueous groundwater solutions with mineral surfaces. Although the liquid-solid interface has been studied for many years, it is only recently that the tools have been developed for interrogating this interface at the atomic level. This interface is particularly complex, as the interactions of ions dissolved in solution with a surface are affected not only by the surface structure, but also by the solution chemistry and by the effects of the electrical double layer [31]. It has been found, for example, that some surface reconstructions present in UHV persist under solution, while others do not. 

The percolation argument is based on the idea that with an increasing Cr content an insoluble interlinked cliromium oxide network can fonn which is also protective by embedding the otherwise soluble iron oxide species. As the tlireshold composition for a high stability of the oxide film is strongly influenced by solution chemistry and is different for different dissolution reactions [73], a comprehensive model, however, cannot be based solely on geometrical considerations but has in addition to consider the dissolution chemistry in a concrete way. 

Decomposition of potassium ferratefVI) at 1000 K gives a ferrate V), K3Fe04, and several types of ferrate(IV), for example FeOj", Fe04 are known these ferrates(IV) have no solution chemistry and are probably best regarded as mixed oxides, since the FeOl" ion has no identifiable structure. 

The example clearly demonstrates the main advantages of solution chemistry over the solid-phase approach ... 

Synthesis. In contrast to pituitary hormones, which usually can be obtained in pure form only after extraction from animal tissues, brain oligopeptides are readily available because of their small size. The synthetic repHca represents the most economical and readily accessible source for the oligopeptides. Two techniques are available for laboratory synthesis of oligopeptides, ie, solution chemistry and soHd-phase peptide synthesis (SPPS). 

Citrates. Iron citrate [2338-05-8] is a compound that contains citric acid and iron(II) and iron(III) in indefinite ratios. Iron(II) citrate [23383-11-1] and iron(III) citrate [28633-45-6] are also of indefinite stoichiometry, although iron(III) citrate which contains Fe and citric acid in a 1 1 ratio [3522-50-7] is known. These compounds dissolve slowly in water and are more readily soluble in hot water. The solution chemistry of these compounds is comphcated by formation of a number of monomeric and oligomeric species. All of the iron citrate compounds are used as supplements to soils and animal diets. 

First Carbonation. The process stream OH is raised to 3.0 with carbon dioxide. Juice is recycled either internally or in a separate vessel to provide seed for calcium carbonate growth. Retention time is 15—20 min at 80—85°C. OH of the juice purification process streams is more descriptive than pH for two reasons first, all of the important solution chemistry depends on reactions of the hydroxyl ion rather than of the hydrogen ion and second, the nature of the C0 2 U20-Ca " equiUbria results in a OH which is independent of the temperature of the solution. AH of the temperature effects on the dissociation constant of water are reflected by the pH. 

PZN-PT, and YBa2Cug02 g. For the preparation of PZT thin films, the most frequently used precursors have been lead acetate and 2irconium and titanium alkoxides, especially the propoxides. Short-chain alcohols, such as methanol and propanol, have been used most often as solvents, although there have been several successful investigations of the preparation of PZT films from the methoxyethanol solvent system. The use of acetic acid as a solvent and chemical modifier has also been reported. Whereas PZT thin films with exceUent ferroelectric properties have been prepared by sol-gel deposition, there has been relatively Httle effort directed toward understanding solution chemistry effects on thin-film properties. 

K. L. Mittal, ed.. Solution Chemistry of Sufactants, Vol. 2, Plenum Press, New York, 1979. 

Physical-Chemical Phenomena. Several physical-chemical phenomena occur when chemical reagents are added to an air-water solid system due to the interaction of the reagents with the air-water, water-sohd, and air-solid interfaces. This causes changes in the solution chemistry in which the particles are suspended. Some of the... 

Ohtaki, H., 1998. Crystallization Processes, Wiley Series in Solution Chemistry, Vol. 3. West Sussex John Wiley Sons. 

The central role of the concept of polarity in chemistry arises from the electrical nature of matter. In the context of solution chemistry, solvent polarity is the ability of a solvent to stabilize (by solvation) charges or dipoles. " We have already seen that the physical quantities e (dielectric constant) and p (dipole moment) are quantitative measures of properties that must be related to the qualitative concept of... 

The interaction between a solute species and solvent molecules is called solvation, or hydration in aqueous solution. This phenomenon stabilizes separated charges and makes possible heterolytic reactions in solution. Solvation is, therefore, an important subject in solution chemistry. The solvation of ions has been most thoroughly studied. 

This approach to solution chemistry was largely developed by Hildebrand in his regular solution theory. A regular solution is one whose entropy of mixing is ideal and whose enthalpy of mixing is nonideal. Consider a binary solvent of components 1 and 2. Let i and 2 be numbers of moles of 1 and 2, 4>, and 4>2 their volume fractions in the mixture, and Vi, V2 their molar volumes. This treatment follows Shinoda. ... 

Many books on chemical kinetics have been published, but few of these are devoted solely or even primarily to solution phase chemical kinetics. Textbooks of physical organic chemistry must deal with solution chemistry, but kinetics is only one part of their subject. From my teaching experience I have concluded that there is no current text that meets the needs, as I interpret them, of the student and practitioner of solution chemical kinetics. 

The aqueous solution chemistry of Al and the other group 13 metals is rather complicated. The aquo ions are acidic with... 

M = Al, Ga, In, Tl). The solution chemistry of Al in particular has been extensively investigated because of its industrial importance in water treatment plants, its use in many toiletry formulations, its possible implication in both Altzheimer s disease and the deleterious effects of acid rain, and the ubiquity of Al cooking utensils.For example, hydrated aluminium sulphate (10-30 gm ) can be added to turbid water supplies at pH 6.5-7.5 to flocculate the colloids, some 3 million tonnes per annum being used worldwide for this application alone. Likewise kilotonne amounts of A1(OH)2.5C1o.5 in concentrated (6m) aqueous solution are used in the manufacture of deodorants and antiperspirants. 

The solution chemistry of nitric acid is extremely varied. Redox data are summarized in Table 11.4 and Fig. 11.9 (pp. 434-8). In... 

In addition to simple dissolution, ionic dissociation and solvolysis, two further classes of reaction are of pre-eminent importance in aqueous solution chemistry, namely acid-base reactions (p. 48) and oxidation-reduction reactions. In water, the oxygen atom is in its lowest oxidation state (—2). Standard reduction potentials (p. 435) of oxygen in acid and alkaline solution are listed in Table 14.10- and shown diagramatically in the scheme opposite. It is important to remember that if or OH appear in the electrode half-reaction, then the electrode potential will change markedly with the pH. Thus for the first reaction in Table 14.10 O2 -I-4H+ -I- 4e 2H2O, although E° = 1.229 V,... 

Acidification of solutions of disulfites regenerates HSO3 and SO2 again, and the solution chemistry of S205 is essentially that of the normal sulfites and hydrogen sulfites, despite the formal presence of S and S (rather than S ) in the solid state. 

G. Gordon, R. G. Kieffer and D. H. Rosenblatt, Progr. Inorg. Chem. 15, 201-86 (1972). The first half of this review deals with the aqueous solution chemistry of chlorous acid and chlorites. 

Sandoz, G., Fujii, C. T. and Brown, B. F., Solution Chemistry Within Stress-corrosion Cracks in Alloy Steels , Corros. Sci., 10, 839 (1970)... 

The Gibbs-Duhem equation is extremely important in solution chemistry and it can be seen from equation 20.171 that it provides a means of determining the activity of one component in a binary solution providing the activity of the other is known. 

The I——12 half-reaction has many applications in aqueous solution chemistry. The use of I- as a reducing agent and I2 as an oxidizing agent, particularly for quantitative purposes, is called iodimetry. 

Under certain condition, however, reactions are still preferably conducted in solution. This is the case e.g., for heterogeneous reactions and for conversions, which deliver complex product mixtures. In the latter case, further conversion of this mixture on the solid support is not desirable. In these instances, the combination of solution chemistry with polymer-assisted conversions can be an advantageous solution. Polymer-assisted synthesis in solution employs the polymer matrix either as a scavenger or for polymeric reagents. In both cases the virtues of solution phase and solid supported chemistry are ideally combined allowing for the preparation of pure products by filtration of the reactive resin. If several reactive polymers are used sequentially, multi-step syntheses can be conducted in a polymer-supported manner in solution as well. As a further advantage, many reactive polymers can be recycled for multiple use. 

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