Numbers of cations

Isopolyanions. Isopolyanions are named by indicating with numerical prefixes the number of atoms of the characteristic element. It is not necessary to give the number of oxygen atoms when the charge of the anion or the number of cations is indicated. 

Table 2 Hsts examples of compounds with taste and their associated sensory quaUties. Sour taste is primarily produced by the presence of hydrogen ion slightly modified by the types of anions present in the solution, eg, acetic acid is more sour than citric acid at the same pH or molar concentration (43). Saltiness is due to the salts of alkaU metals, the most common of which is sodium chloride. However, salts such as cesium chloride and potassium iodide are bitter potassium bromide has a mixed taste, ie, salty and bitter (44). Thus saltiness, like sourness, is modified by the presence of different anions but is a direct result of a small number of cations.

A number of cationic muds have been developed and used. These ate formulated around quaternary amines or positively charged polymers (108,109). The polymer in some iastances may be a cationic polyacrylamide. Poly(dimethylarnine-fi9-epichloiohydrin) is another material that has been used successfiiUy for drilling shale formations (110,111). Some of these additives may requite a salt such as sodium or potassium chloride for best results. 

Antimonic acid has been used as an ion-exchange material for a number of cations in acidic solution. Most interesting is the selective retention of Na" in 12 Af HQ, the retention being 99.9% (24). At lower acidities other cations are retained, even K". Many oxidation and polymerization catalysts are listed as containing Sb203. 

Table 1. Transference Number of Cations, Anions t, and Electrons or Holes in Several Compounds...

In mixed-bed units, both the cation and the anion resins are mixed together thoroughly in the same vessel by compressed air. The cation and the anion resins being next to each other constitute an infinite number of cation and anion exchangers. The effluent quality obtainable from a well-designed and operated mixed-bed exchanger will readily produce demineralized water of conductivity less than 0.5 mmho and silica less than 10 ppb. 

Strategy Once you deduce the formula of the ionic compound, it s all downhill. Remember, though, that you have to show the relative numbers of cations and anions. 

EDTA forms 1 1 complexes with a large number of cations, including those of some of the main-group metals. The complex formed by calcium with EDTA is used to treat lead poisoning. When a... 

The ratio between the anionic and cationic radii leads to coordination numbers, the lowest of which is 6, which correspond to a octahedral polyhedron of anions around a central cation [135]. In this case, the compound structure type depends on the ratio of total number of anions and cations. The total number of anions (X) is calculated by summing up the number of oxygen (O) ions and of fluorine (F) ions X=0+F, while the total number of cations (Me) is the number of tantalum ions, niobium ions and other similar cations. 

The rate of product formation can be predicted from a knowledge of the conductivity and transport numbers of cations in the product barrier phase and appropriate thermodynamic data. This interpretation is based on the Wagner model (Sect. 2.3). 

The formulas of ionic compounds have a different meaning from those of molecular compounds. Each crystal of sodium chloride has a different total number of cations and anions. We cannot simply specify the numbers of ions present as the formula of this ionic compound, because each crystal would have a different formula and the subscripts would be enormous numbers. However, the ratio of the number of cations to the number of anions is the same in all the crystals, and the chemical formula shows this ratio. In sodium chloride, there is one Na+ ion for each Cl ion so its formula is NaCl. Sodium chloride is an example of a binary ionic compound, a compound formed from the ions of two elements. Another binary compound, CaCl2, is formed from Ca2+ and Cl- ions in the ratio 1 2, which is required for electrical neutrality. 

Calculate the number of cations, anions, and formula units per unit cell in each of the following solids (a) the cesium chloride unit cell shown in Fig. 5.41 (b) the rutile (Ti02) unit... 

A number of cationic Cr(I) species of the type depicted have been... 

Peptoid hbraries have also yielded compounds active in the disruption of RNA-protein interactions. Compounds not derived from library syntheses are discussed in Section 1.4.1. A peptoid 9-mer with a number of cationic groups was discovered (Fig. 1.4) after several rounds of mixture deconvolution, that was able to block the interaction of HIV-1 Tat protein with TAR RNA at nanomolar concentra-... 

Fig. 3.4 Polyamide-DNA binding motifs with equilibrium association constants K,). Hairpin amino-substitution at the a-position of the y-turn residue leads to enhanced binding affinity (10-fold) without loss of specificity, and with higher orientational selectivity and offers potential for further substitution. Cycle Cyclic polyamides show higher affinity than analogous hairpin molecules with the same number of cationic groups and eliminate all possibility of extended 1 1 binding. H-pin and U-pin compared to their non-linked analogs, H-pins and U-pins exhibit higher binding affinity. The black and open circles represent Im and Py rings, respectively diamonds repre-...

Therefore, an ideal polymer electrolyte must be flexible (associated with a low Tg), completely amorphous, and must have a high number of cation-coordination sites to assist in the process of salt solvatation and ion pair separation (see Table 11). A review on this subject has been recently published by Inoue [594]. 

John D. Corbett once said There are many wonders still to be discovered [4]. This certainly holds generally for all the different areas and niches of early transition cluster chemistry and especially for the mixed-hahde systems. The results reported above so far cover a very Hmited selection of only chloride/iodide systems and basically boron as the interstitial. Because of the very sensitive dependence of the stable stracture built in the soHd-state reaction type on parameters like optimal bonding electron counts, number of cations present, size and type of cations (bonding requirements for the cations), metal/halide ratio, and type of halide, a much larger mixed-hahde cluster chemistry can be expected. Further developments, also in mixed-hahde systems, can be expected by using solution chemistry of molecular clusters, excised from solid-state precursors. 

Number of cations, anions, and total ions v = Vj,+vJ) into which the given electrolyte dissociates (Chap. XIII). 

The values of hj for different ions are between 0 and 15 (see Table 7.2). As a rule it is found that the solvation number will be larger the smaller the true (crystal) radius of the ion. Hence, the overall (effective) sizes of different hydrated ions tend to become similar. This is why different ions in solution have similar values of mobilities or diffusion coefficients. The solvation numbers of cations (which are relatively small) are usually higher than those of anions. Yet for large cations, of the type of N(C4H9)4, the hydration number is zero. 

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