Ion cations

The electrolyte thus formed can conduct electric current by the movement of ions under the influence of an electric field. A cell using an electrolyte as a conductor and a positive and a negative electrode is called an electrolysis cell. If a direct-current voltage is appHed to a cell having inert electrode material such as platinum, the hydrogen ions (cations) migrate to the cathode where they first accept an electron and then form molecular hydrogen. The ions... 

Chemical analyses of stream water that have been pubhshed since the early years of this century generally include deterrninations for four positively charged ions (cations)—calcium (Ca ), magnesium (Mg ), sodium (Na ), and potassium (K )—and five negatively charged ions... 

The azo coupling reaction proceeds by the electrophilic aromatic substitution mechanism. In the case of 4-chlorobenzenediazonium compound with l-naphthol-4-sulfonic acid [84-87-7] the reaction is not base-catalyzed, but that with l-naphthol-3-sulfonic acid and 2-naphthol-8-sulfonic acid [92-40-0] is moderately and strongly base-catalyzed, respectively. The different rates of reaction agree with kinetic studies of hydrogen isotope effects in coupling components. The magnitude of the isotope effect increases with increased steric hindrance at the coupler reaction site. The addition of bases, even if pH is not changed, can affect the reaction rate. In polar aprotic media, reaction rate is different with alkyl-ammonium ions. Cationic, anionic, and nonionic surfactants can also influence the reaction rate (27). 

Current flow through the frits is supported by ions. Cations and anions both support the virtual current by flowing in opposite directions, and the transference number of a particular ion is defined as the fraction of the total current it carries. The sum of all transference numbers then is necessarily unity. If the fraction of the virtual current carried by the cations equals the fraction carried by the anions then the solution is said to be equitransferent. 

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

POSITIVE IONS (cations) negative ions (anions) ... 

There has been much interest in modifying the ion-exchange properties of conducting polymers with substituents or polymeric counter-ions. Cationic substituents, such as ammonium234 and pyridinium235 groups, increase the polymer s anion-exchange capacity and increase anion trans-... 

Reactive radical ions, cations and anions are frequent intermediates in organic electrode reactions and they can serve as polymerization initiators, e.g. for vinylic polymerization. The idea of electrochemically induced polymerization of monomers has been occasionally pursued and the principle has in fact been demonstrated for a number of polymers But it appears that apart from special cases with anionic initiation the heterogeneous initiation is unfavorable and thus not competitive for the production of bulk polymers A further adverse effect is the coating of electrodes... 

Bulk structures of oxides are best described by assuming that they are made up of positive metal ions (cations) and negative O ions (anions). Locally the major structural feature is that cations are surrounded by O ions and oxygen by cations, leading to a bulk structure that is largely determined by the stoichiometry. The ions are, in almost all oxides, larger than the metal cation. It does not exist in isolated form but is stabilized by the surrounding positive metal ions. 

Winstein Robinson (1958) used this concept to account for the kinetics of the salt effects on solvolysis reactions. They considered that carbonium ions (cations) and carbanions could exist as contact ion-pairs, solvated ion-pairs and as free ions and that all these forms participated in the reactions and were in equilibrium with each other. These equilibria can be represented, thus ... 

The first example relates dissolution of zinc metal. This pertains to Figure 5.2 (A) which provides the answer for conditions of dissolution. The dissolution of a metal is electrochemical in nature and, as the potential for the dissolution of zinc is more negative than both of the above reactions, each of them can serve as a cathodic process to support the anodic dissolution of zinc. It may be seen from Figure 5.2 (A) that solubilization is favorably disposed below a pFF of about 6.9 with the production of Zn2+ ions (cations) and beyond a pH of about 13.4 with the formation ZnO ions (anions). 

Naming of the positive ion depends on whether the cation is monatomic (has one atom). If not, the special names given in Sec. 6.3.2 are used. If the cation is monatomic, the name depends on whether the element forms more than one positive ion in its compounds. For example, sodium forms only one positive ion in all its compounds—NaT Iron forms two positive ions—Fc2r and Fe,+. Cations of elements that form only one type of ion in all their compounds need not be further identified in the name. Thus, Na may simply be called the sodium ion. Cations of metals that occur with two or more different charges must be further identified. Fe(NO,)2 and Fe(NO,)3 occur with Fc2+ and Fe3 ions, respectively. If we just call the ion the iron ion, we will not know which one it is. Therefore, for monatomic cations, we use a Roman numeral in parentheses attached to the name to tell the charge on such ion. (Actually, oxidation numbers are used for this purpose, but if you have... 

Cation-selective ionophores are the most successful in polymeric ISEs and selectivi-ties exceeding ten orders of magnitude became quite common. The cation-ionophore binding occurs dominantly due to Lewis interactions and could be understood in terms of hard and soft acid and bases theory (HSAB). While hard base oxygen atoms originate from ester, ether or carbonyl functionalities, and interact with hard acid alkaline cations, the softer sulfur or nitrogen atoms better bind with transition metal ions. Cation... 

An electrically charged atom or group of atoms. An atom which loses an electron becomes a positive ion (cation) and one which gains an electron becomes a negative ion (anion). In electrolysis anions are attracted to the anode and cations to the cathode, lonomer... 

The attractions between positive ions (cations) and negative ions (anions) are strong, and ionic compounds have a giant lattice stmcture. 

Structural Unit ions cations surrounded by mobile "sea" of electrons atoms polar or nonpolar molecules... 

The number of positively charged ions (cations) in the body must always be equal to the number of those negatively charged (anions). However, some negatively charged substances are not measured by the clinical laboratory tests, resulting in a net deficiency of anions between 8 to 16 milliequivalents/ liter. This value is commonly referred to as the anion gap, and it may be estimated as follows ... 

This attraction is due to the attraction of an ion (cation or anion) with one end of a polar molecule (dipole). This type of attraction is especially important in aqueous salt solutions where the ion attracts water molecules and may form a hydrated ion (i.e., A1(H20) +). 

A typical gel electrophoresis apparatus is shown in Figure 11.23. The thin gel slab referred to above is contained between two glass plates. The slab is held in a vertical position and has notches at the top where the samples to be separated are spotted or streaked. In the configuration shown in the figure, only downward movement takes place, and thus only one type of ion, cation or anion, can be separated, since there is only one direction to go from the notch. 

The coefficients a, and b are dependent on temperature and the type of ion (cations, OH- and simple anions, oxyanions and acid oxyanions) and have been established by Criss and Cobble by analyzing available experimental data. SiggCabsolute) is the 298°K entropy on an absolute sca e corresponding to the partial molal entropy of H (aq) as -5.0 cal deg" mole-1 at 298°K. The absolute and conventional partial molal entropy for any ion are related by... 

The ionic divide , at group 18, separates elements at its immediate right, which easily form positive ions (cations), from those (halogens, chalcogens) which easily form negative ions (anions). 

L. F. Lindoy, in Mixed-donor macrocycles solution and structural aspects of their complexation with transition and post-transition ions, Cation Binding by Macrocycles (Y. Inoue and G. W. Gokel, eds.), p. 599, Marcel Dekker, New York (1990). 

Heterocycles are of great interest in organic chemistry due to their specific properties. Many of these cycles are widely present in natural and pharmaceutical compounds. Electrochemistry appears as a powerful tool for the preparation and the functionalization of various heterocycles because anodic oxidations and cathodic reductions allow the selective preparation of highly reactive intermediates (radicals, radical ions, cations, anions, and electrophilic and nucleophilic groups). In this way, the electrochemical technique can be used as a key step for the synthesis of complex molecules containing heterocycles. A review of the electrolysis of heterocyclic compounds is summarized in Ref. [1]. 

Ionic solids are also called salts. Salts are composed of atoms held together by ionic bonds. These bonds are the result of electrostatic attractions between positively charged ions (cations ) and negatively charged ions (anions). The force of electrostatic attraction is inversely related to the square of the distance of separation of the ions (Eq. 2.1). 

Through the presence of aromatic or pseudoaromatic groups in the molecule (tetraphenylborate and related derivatives, the tetraphenyl-arsonium ion, cationic triphenylmethane dyes, complexes of o-phenanthroline with divalent nickel or ion, where the hydrophobicity is increased by further substitution by a hydrophobic group on the pseudoaromatic nucleus). 

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