Soluble ions

Hydrated Stannic Oxide. Hydrated stannic oxide of variable water content is obtained by the hydrolysis of stannates. Acidification of a sodium stannate solution precipitates the hydrate as a flocculent white mass. The colloidal solution, which is obtained by washing the mass free of water-soluble ions and peptization with potassium hydroxide, is stable below 50°C and forms the basis for the patented Tin Sol process for replenishing tin in staimate tin-plating baths. A similar type of solution (Staimasol A and B) is prepared by the direct electrolysis of concentrated potassium staimate solutions (26). 

The high electrical resistivity of asbestos fibers is weU-known, and has been widely exploited in electrical insulation appHcations. In general, the resistivity of chrysotile is lower than that of the amphiboles, particularly in high humidity environments (because of the availabiHty of soluble ions). For example, the electrical resistivity of chrysotile decreases from 1 to 2100 MQ/cm in a dry environment to values of 0.01 to 0.4 MQ/cm at 91% relative humidity. Amphiboles, on the other hand, exhibit resistivity between 8,000 and 900,000 MQ/cm. 

The tri- or tetraamine complex of copper(I), prepared by reduction of the copper(II) tetraamine complex with copper metal, is quite stable ia the absence of air. If the solution is acidified with a noncomplexiag acid, the formation of copper metal, and copper(II) ion, is immediate. If hydrochloric acid is used for the neutralization of the ammonia, the iasoluble cuprous chloride [7758-89-6], CuCl, is precipitated initially, followed by formation of the soluble ions [CuClj, [CuCl, and [CuCl as acid is iacreased ia the system. 

The slightly soluble ion pair was used as electrode-active substance in a plastered membrane of an ion-selective electrode (ISE) for these alkaloids. 

Ammonia NH3 Corrosion of copper and zinc alloys by formation of complex soluble ion Cation exchange with hydrogen zeolite, chlorination, deaeration, mixed-bed demineralization... 

Figure 5.11 (Crisp Wilson, 1974b) shows the time-dependent variation of the concentration of soluble ions in setting and hardening cements. Note that the concentrations of aluminium, calcium and fluoride rise to maxima as they are released from the glass. After the maximum is reached the concentration of soluble ions decreases as they are precipitated. Note that this process is much more rapid for calcium than for aluminium and the sharp decline in soluble calcium corresponds to gelation. This indication is supported by information from infrared spectroscopy which showed that gelation (initial set) was caused by the precipitation of calcium polyacrylate. This finding was later confirmed by Nicholson et al. (1988b) who, using Fourier transform infrared spectroscopy (FTIR), found that calcium polyacrylate could be detected in the cement paste within one minute of mixing the cement. There was no evidence for the formation of any aluminium polyacrylate within nine minutes and substantial amounts are not formed for about one hour (Crisp et al, 1974).

Figure 5.11 The time-dependent variation, in setting and hardening cements, of the concentration of soluble ions Al ", Ca, F and PO (expressed as P Oj). These ions are released from the glass powder into the cement matrix (Crisp Wilson, 1974b).

Figure 6.15 The time-dependent variation of the concentration of soluble ions during the setting and hardening of a dental sihcate eement (Wilson Kent, 1970b).

Extraction studies have also been carried out by grinding the ageing cements and extracting the soluble ions with water (Wilson Kent, 1970 Crisp Wilson, 1974). Ion content was determined using atomic absorption spectroscopy. The experiments give different, but complementary, results to those of Cook (1983), since what is extracted are those ions that have been released from the glass powder but not yet insolubilized by reaction with the polyacid. 

The metal is ionized in the anodic process to produce soluble ions. 

The second model of a biological membrane is the liposome (lipid vesicle), formed by dispersing a lipid in an aqueous solution by sonication. In this way, small liposomes with a single BLM are formed (Fig. 6.11), with a diameter of about 50 nm. Electrochemical measurements cannot be carried out directly on liposomes because of their small dimensions. After addition of a lipid-soluble ion (such as the tetraphenylphosphonium ion) to the bathing solution, however, its distribution between this solution and the liposome is measured, yielding the membrane potential according to Eq. 

Biological activity can be used in two ways for the bioremediation of metal-contaminated soils to immobilize the contaminants in situ or to remove them permanently from the soil matrix, depending on the properties of the reduced elements. Chromium and uranium are typical candidates for in situ immobilization processes. The bioreduction of Cr(VI) and Ur(VI) transforms highly soluble ions such as CrO and UO + to insoluble solid compounds, such as Cr(OH)3 and U02. The selenate anions SeO are also reduced to insoluble elemental selenium Se°. Bioprecipitation of heavy metals, such as Pb, Cd, and Zn, in the form of sulfides, is another in situ immobilization option that exploits the metabolic activity of sulfate-reducing bacteria without altering the valence state of metals. The removal of contaminants from the soil matrix is the most appropriate remediation strategy when bioreduction results in species that are more soluble compared to the initial oxidized element. This is the case for As(V) and Pu(IV), which are transformed to the more soluble As(III) and Pu(III) forms. This treatment option presupposes an installation for the efficient recovery and treatment of the aqueous phase containing the solubilized contaminants. 

Soils and vadose zone information, including soil characteristics (type, holding capacity, temperature, biological activity, and engineering properties), soil chemical characteristics (solubility, ion specification, adsorption, leachability, cation exchange capacity, mineral partition coefficient, and chemical and sorptive properties), and vadose zone characteristics (permeability, variability, porosity, moisture content, chemical characteristics, and extent of contamination)... 

The soluble ion Al(OH) (aq) is known as the aluminate ion. The vigorous evolution of hydrogen gas helps to physically dislodge undissolved grease particles from the walls of plumbing. 

All of the methods described and referenced here are capable of producing high-quality, accurate results, but only if the raw data are correctly interpreted and analyzed to detect (and correct) for issues arising from issues such as low solubility, ion pair partition or multiple ionizable groups with overlapping pKas. It is not... 

The reaction of diorganozincs bearing bulky trimethylsilyl-substituted methyl groups and methyl- or phenyllithium in the presence of the 1,3,5-trimethyl-1,3,5-triazacyclohexane (TAGH), Scheme 53, afforded the corresponding lithium zincates as poorly soluble ion pairs.124... 

The structural and formulaic questions concerning compounds such as (4.66a)-(4.66c) were largely resolved by Alfred Werner,31 the first inorganic chemist to receive a Nobel Prize (1913). Werner carefully studied the total number of free ions contributing to ionic conductivity, as well as the number of free chloride ions that could be precipitated (exchanged with a more soluble ion) under conditions of excess Ag+, namely... 

There is little doubt that cryotechniques, and particularly cryo-SEM, are now the dominant methods of specimen preparation for electron probe X-ray microanalysis when localization of soluble ions is required. In a previous review (5) these techniques were covered in considerable detail and this material is not reiterated here. Instead, protocols for the two major methods are provided and some recent developments and publications in this area are highlighted. 

The soluble ions of iron and aluminium are usually reduced to a minimum by adjusting the electrolyte pH. For the removal of solid iron hydroxide and aluminium hydroxide Bayer decided to use a new pre-coat-free brine purification technology -back-pulse filtration using GORE-TEX membrane filter cloths. 

As one may expect from the diversity of microorganisms that can reduce iron, the spectrum ranges from bacteria that can use only amorphous Fe(III) hydroxide/oxide (e.g., T. ferrireducens) and apparently require direct contact with the Fe(III) precipitate, as shown by electron micrographs (Slobodkin et al. 1997b), to bacteria that can utilize various forms of Fe(III) ion as precipitated hydroxide or as complexed soluble ions, such as Fe(III) citrate, to bacteria such as T. saccharolyticum that can use only soluble Fe(III) citrate but are stimulated by the addition of increased Fe(III) ions. Further studies must to be done to elucidate the nature and which of the bacteria excrete electron mediators (so no direct contact would be required) and which contain cell-wall-bound reductases (which require a direct contact with the Fe(III) precipitate). 

A polyelectrolyte solution contains the salt of a polyion, a polymer comprised of repeating ionized units. In dilute solutions, a substantial fraction of sodium ions are bound to polyacrylate at concentrations where sodium acetate exhibits only dissoci-atedions. Thus counterion binding plays a central role in polyelectrolyte solutions [1], Close approach of counterions to polyions results in mutual perturbation of the hydration layers and the description of the electrical potential around polyions is different to both the Debye-Huckel treatment for soluble ions and the Gouy-Chapman model for a surface charge distribution, with Manning condensation of ions around the polyelectrolyte. 

In recent years, experience has shown that a large number of hydrophobic ions could act as ion-exchanger ions in liquid membranes and that almost all water soluble ions not unusually hydrophilic, such as Li, may produce a response in such an ISE. These facts have led to an extraordinary increase in publications in this field, although relatively few of these ISEs have actually been used to solve analytical problems. This field, which is becoming rather confused, will not be discussed in this book and the reader is referred to reviews [103-105]. 

Aromatic electrophilic substitution is used commercially to produce styrene polymers with ion-exchange properties by the incorporation of sulfonic acid or quaternary ammonium groups [Brydson, 1999 Lucas et al., 1980 Miller et al., 1963]. Crosslinked styrene-divinyl-benzene copolymers are used as the starting polymer to obtain insoluble final products, usually in the form of beads and also membranes. The use of polystyrene itself would yield soluble ion-exchange products. An anion-exchange product is obtained by chloromethylation followed by reaction with a tertiary amine (Eq. 9-38) while sulfonation yields a cation-exchange product (Eq. 9-39) ... 

In electrochemical etching of metals the plate and a counterelectrode are placed in a liquid electrolyte and a voltage is applied to create an electric field between the plates to dissolve the metal as soluble ions. Discuss the following issues and sketch configurations and profiles. 

In this profile, the term chlorite will be used to refer to chlorite ion, which is a water-soluble ion. Chlorite ion will combine with metal ions to form solid salts, (e.g., sodium chlorite). In water, sodium chlorite is soluble and will dissolve to form chlorite ions and sodium ions. More than 80% of all chlorite (as sodium chlorite) is used to make chlorine dioxide to disinfect drinking water. Sodium chlorite is also used as a disinfectant to kill germs. 

Step (1). Species identification. Perusal of descriptive inorganic chemistry texts will lead to the discovery of the Ga-, 0-, and H-containing species which persist in water. These species consist of the solids Ga and Ga(OH)3 and the soluble ions Ga+ and Ga(OH)4. It should be noted that Ga(OH)3 should occur in the basic region and that Ga will sit low on the E-pH diagram because it is the most highly reduced species. 

The mechanism by which cations are transported across a membrane is represented in Figure 18a. A cation-carrier complex is initially formed at the interface. This lipophilic species then diffuses across the membrane as an ion pair and dissociates at the other interface to water soluble ion pair and membrane-soluble carrier. The final step is back diffusion of the free carrier to the initial interface. The factors which influence transport rates and selectivity have been the subject of much research (79PAC979, B-81MI52102). 

The transmembrane potential of cardiac cells is determined by the concentrations of several ions—chiefly sodium (Na+), potassium (K+), calcium (Ca2+), and chloride (Cl-)—on either side of the membrane and the permeability of the membrane to each ion. These water-soluble ions are unable to freely diffuse across the lipid cell membrane in response to their electrical and concentration gradients they require aqueous channels (specific pore-forming proteins) for such diffusion. Thus, ions move across cell membranes in response to their gradients only at specific times during the cardiac cycle when these ion channels are open. The movements of the ions produce currents that form the basis of the cardiac action potential. Individual channels are relatively ion-specific, and the flux of ions through them is... 

A RhCl3-Dowex 1 anion exchanger ion pair is an efficient and recyclable catalyst to induce hydration of acetylenes.560 Whereas the soluble ion pair mediates oligomerization, this solid catalyst transforms phenylacetylenes to the corresponding methyl ketones in high yields. 

The solubility product does not tell the entire story of solubility. In addition to compli-A salt is any ionic solid, such as Hg2Cl2 or cations described in Box 6-1, most salts form soluble ion pairs to some extent. That is,... 

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