Counterion anion

The ion transport number is defined as the fraction of current carried through the membrane by counterions. If the concentration of fixed charges in the membrane is high compared to the concentration of the ambient solution, then the mobile ions in the IX membrane are mosdy counterions, co-ions are effectively excluded, and the ion transport number then approaches 1. Commercial membranes have ion transport numbers in dilute solutions of ca 0.85—0.95. The relationship between ion transport number and current efficiency is shown in Figure 3 where is the fraction of current carried by the counterions (anions) through the AX membrane and is the fraction of current carried by the counterions (cations) through the CX membrane. The remainder of the current (1 — in the case of the AX membranes and (1 — in the case of the CX membranes is carried by co-ions and... 

Suspend the gel in a buffer with the same pH as the starting buffer, but tenfold concentrated with respect to the buffering counterion (anion exchange medium, e.g., phosphate). Pour the gel into the column after 15 min and wash it with 10 ml starting buffer per gram wet weight. 

C. Preparation. As indicated by the E-pH diagram, the ammonium ion NH4+ can be prepared by acidifying a basic solution of NH4OH (actually hydrated NH3) until a pH of 9.2 or below is attained. The counterion (anion) associated with the NH4 is determined by the anion of the acid used in the acidification. The precursor of NH4 , namely NH3, is produced by the reaction of N2 with H2 at an elevated temperature in the presence of a catalyst. The H2 for this reaction is generated from various substances including coke and natural gas (CH4). 

FIGURE 1.5 Concentrations of counterions (anions) (x) and coions (cations) n+ x) around a positively charged planar surface (arbitrary scale). Calculated from Eqs. (1.3) and (1.26)foryo = 2. 

Figure 1.11 gives the scaled potential distribution y(r) around a positively charged spherical particle of radius a with yo = 2 in a symmetrical electrolyte solution of valence z for several values of xa. Solid lines are the exact solutions to Eq. (1.110) and dashed lines are the Debye-Hiickel linearized results (Eq. (1.72)). Note that Eq. (1.122) is in excellent agreement with the exact results. Figure 1.12 shows the plot of the equipotential lines around a sphere with jo = 2 at ka = 1 calculated from Eq. (1.121). Figures 1.13 and 1.14, respectively, are the density plots of counterions (anions) (n (r) = exp(+y(r))) and coions (cations) ( (r) = MCxp(—y(r))) around the sphere calculated from Eq. (1.121). 

FIGURE 1.13 Density plots of counterions (anions) around a positively charged spherical particle with yo 2 at xa—l. Calculated from n r) — nexp(+y(r)) with the help of Eq. (1.121). The darker region indicates the higher density and u (r) tends to its bulk value n far from the particle. Arbitrary scale. 

The choice of counterions (anions) in the cationic polymerization of heterocyclic monomers can be almost as wide as in anionic polymerization, but only for the most nucleophilic monomers (i. e. cyclic amines). Unfortunately, in the polymerization of cyclic ethers, this choice is much more restricted. Thus, the small anions like F or OH cannot be used because, due to their high nucleophilicity and ability to form covalent bonds, they give rise to fast termination. In order to suppress or even to eliminate termination by collapse within an ton pair (cf. Sect. 5.1.), it is necessary to use complexed anions having large ionic radii. These are shown below (rctyst)-... 

The choice of counterion (anion or cation) has a major effect on the stability of conducting polymers. The stability of donor- (36) and acceptor-doped (37, 38) polyacetylenes, polypyrrole (39), poly(alkylthiophene)s (40), and other polymers (40) has been studied by using thermogravimetric anal-... 

Counterions anions or cations that balance the charge on the complex ion in a coordination compound. (21.3)... 

The properties of the counterion (e.g. its size, geometry and charge) influence the properties of the polymer, the amount of counterion (anion) incorporated depends on the reaction conditions. In general, one anion is incorporated for every diree pyrrole units. Exceptions are pyrrole-and thiophene-sulfonic acids, where the counterion is coupled directly to the monomer (self-doping) [24]. Some typical conducting anions are fluoroborate, perchlorate, aromatic sulfonic... 

Head group Counterion Anionic -OSO4 Sodium Cationic -N(CH3)t Bromide Non-ionic (0CH2CH2)60H... 

Cao et al. [36] reported that difficulties in the processing of PANI in the conductive form from reasonably high molecular weights could be overcome by the use of a functionalized protonic acid. This functionalized system dopes PANI and simultaneously renders the conductive PANI complex soluble in common organic acids. In this study the authors defined a functionalized protonic acid as H (M —R) in which the counterion anionic... 

Transition metal ions characteristically form coordination compounds, which are usually colored and often paramagnetic. A coordination compound typically consists of a complex ion, a transition metal ion with its attached ligands (see Section 15.8), and counterions, anions or cations as needed to produce a compound with no net charge. The substance [Co(NH3)5Cl]Cl2 is a typical coordination compound. The brackets indicate the composition of the complex ion, in this case Co(NH3)5Cl, and the two d counterions are shown outside the brackets. Note that in this compound one Cl acts as a ligand along with the five NH3 molecules. In the solid state this compound consists of the large Co(NH3)5Cl cations and twice as many Cl anions, all packed together as efficiently as possible. When dissolved in water, the solid behaves like any ionic solid the cations and anions are assnmed to separate and move about independently ... 

Presendy this phenomenon is explained by the possibility of forming a n electron complex between carbocation located at the end of the chain and the new monomer molecule, rather than a covalent bond. It takes place during the attachment of a free radical to the monomer molecule. A large impact on the growth rate may have also the used solvent because of the differences in solvation of the growing ion. The use of a solvent of relatively low dielectric constant in the polymerization process causes that the ends of the chain appear mainly as a pair of ion with the counterion. Anion located near carbocation may also affect die growth rate, what makes the whole process more complex. 

The rate of excess charge deposition in the sprayed fluid is given by the current supplied by the power supply in the circuit. The rate of flow of the sprayed solution is either forced by an external pump or created by the electrospray process. In either case, the molar concentration of excess charge, [Q], is the ratio of the charge and solution flows as given by Eq. (2.1). As mentioned before, a typical value of [Q] for normal electrospray is 10 M. This is a much smaller concentration than the sum of the total ionic species in the solution, so it follows that some of the ions will be the carriers of the excess charge and others will not. Those that are not will be paired with an equivalent number of counterions (anions, in the case of positive ESI). An immediately obvious consequence of this postulate is that [Q is the maximum mole-charge concentration of ions in the solution that can be converted to vapor phase ions. 

The carbocation reacts both in the stable form and in the composition of the ion pair. This explains the fact that the counterion (anion) influences on the ratio of solvolysis of H+ detachment resulting in the formation of olefin. In the solvolysis of C2H5(CH3)2CX in 80% C2H5OH (298 K), the fraction of olefin in the reaction prod-... 

The most remarkable EDOT reactions are its oxidation reactions, typically resulting in conductive oligomeric to polymeric materials in the presence of charge balancing, so-called doping counterions (anions). These reactions and syntheses will be discussed in detail later (Chapters 7 through 9). 

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