Cation, increased concentration

Stability constants of the complexes formed between Pu(III), Pu(IV), and HSOi, were determined in 1 M acid media by measuring the decrease in extraction (either into TTA-toluene or ion-exchange resin) with increasing concentration of HSO4 in the aqueous solution. Because of very different degrees of extraction for Pu(III) and Pu(IV) and the imposed requirement of 1 M acidity, Pu(IV)-HSOit complexation was studied by TTA extraction, while the Pu(III)-HSOit system was studied by cation exchange. 

Surfactants have a unique long-chain molecular structure composed of a hydrophilic head and hydrophobic tail. Based on the nature of the hydrophilic part surfactants are generally categorized as anionic, non-ionic, cationic, and zwitter-ionic. They all have a natural tendency to adsorb at surfaces and interfaces when added in low concentration in water. Surfactant absorption/desorption at the vapor-liquid interface alters the surface tension, which decreases continually with increasing concentrations until the critical micelle concentration (CMC), at which micelles (colloid-sized clusters or aggregates of monomers) start to form is reached (Manglik et al. 2001 Hetsroni et al. 2003c). 

Support for the involvement of Fe comes from the observation that the kinetic chain length of the dimethyl ester increases with increasing concentration of added Fe together with a fourfold increase in the yield of 262 (216). However, as a vinyl cation bearing carbonyl substituents may be energetically unfavorable, an alternative mechanism, involving a ligand transfer from hydrated Fe ions followed by an acid-catalyzed cyclization, may be a more likely pathway ... 

In KCl, the time dependence showed a marked decrease as the concentration was increased, becoming practically independent of time at a concentration of 1.0 M. This could be explained by adsorbed layers of cations on the surfaces, which reduce the attractive force between them. Further, this reduction with concentration became greater as the hydration enthalpy of the cations increased. This was interpreted in terms of the observations of Hi-... 

Type II refers to the case in which the isotherms for both cations increase with increasing concentration of the respective cations. Such isotherms have been found for (Li, K)F,j2 (Li, K)(S04)i/2, (Na, K)OH, (Ag, Cs)Br, - (Ag, Na)I, - (Ag, K)I, - " and (Ag, CS)I. In charge asymmetric systems such as (K, Ca 2)CI, such isotherms also usually appear. A common feature of these type II systems is the particularly strong interaction of one cation with the common anion compared with that of the second cation with the anion. The strongly interacting cation will retard the internal mobility of the second cation. This is called the tranquilization effect, and will be explained in Section III.5( 70-... 

In such systems as (M, Mj (i/2))X (M, monovalent cation Mj, divalent cation X, common anion), the much stronger interaction of M2 with X leads to restricted internal mobility of Mi. This is called the tranquilization effect by M2 on the internal mobility of Mi. This effect is clear when Mj is a divalent or trivalent cation. However, it also occurs in binary alkali systems such as (Na, K)OH. The isotherms belong to type II (Fig. 2) % decreases with increasing concentration of Na. Since the ionic radius of OH-is as small as F", the Coulombic attraction of Na-OH is considerably stronger than that of K-OH. 

As the poly(alkenoic acid) ionizes, polymer chains unwind as the negative charge on them increases, and the viscosity of the cement paste increases. The concentration of cations increases until they condense on the polyadd chain. Desolvation occurs and insoluble salts precipitate, first as a sol which then converts to a gel. This represents the initial set. 

We see that in binary electrolytes, the flux of the reacting cation increases by a factor of 1 + (x /x+) relative to the pure diffusion current that would be observed (at a given concentration gradient) in the presence of an excess of foreign electrolyte. We shall call... 

The presence of salts of univalent and bivalent cations increases, by several-fold, the activity of pectinesterases from higher plants, which is minimal in the absence of salts.38,50,57,6, 63,64 66,69,7° The activating effect of salts on pectinesterases of microbial origin is not so great, an increase by 1.5- to 2-fold being reported.51 56,63 76-78,80 Table III shows the concentrations of sodium chloride and calcium chloride that caused the maximal activation of pectinesterases of plant and microbial origin. The mechanism of activation has not yet been satisfactorily explained. 

Rate constants of bimolecular, micelle-assisted, reactions typically go through maxima with increasing concentration of inert surfactant (Section 3). But a second rate maximum is observed in very dilute cationic surfactant for aromatic nucleophilic substitution on hydrophobic substrates. This maximum seems to be related to interactions between planar aromatic molecules and monomeric surfactant or submicellar aggregates. These second maxima are not observed with nonplanar substrates, even such hydrophobic compounds as p-nitrophenyl diphenyl phosphate (Bacaloglu, R. 1986, unpublished results). 

It appears that the concentration of surface cations increases with increasing cathodic polarization (decreasing 4< >h ) whereas, the concentration of surface anions increases with increasing anodic polarization (increasing 4h). The dependence of the concentration of surface constituents on suggests that the dissolution rate of MX is determined by the transfer of cations at less anodic potentials and by the transfer of anions at more anodic potentials. 

Equation 9-54 indicates that when tiie electrode interface is in the state of band edge level pinning is constant), the concentration of surface cations increases with increasing anodic polarization. 

Increases in soil salinity can hinder the growth of plants by limiting their uptake of nutrients (Grattan and Grieve 1992). The major cations that affect saline soils are Na", Ca ", Mg ", as well K", while the major anions are CP, SO4, HCOj" and NOj". When the soil has a high pH, COf is also present. The nutrients which plants require most are Ca ", Mg " and K". However, the uptake of and Ca " is hindered by the presence of excess Na", and an increased concentration of Ca " in the soil can lead to a deficiency of Mg " (Grattan and Grieve 1992). 

The difference between the two reactions of Scheme 2.9 may also be considered in terms of the complete electron transfer in both cases. If the a-nitrostilbene anion-radical and metallocomplex cation-radical are formed as short-lived intermediates, then the dimerization of the former becomes doubtful. The dimerization under electrochemical conditions may be a result of increased concentration of reactive anion-radicals near the electrode. This concentration is simply much higher in the electrochemical reaction because all of the stuff is being formed at the electrode, and therefore, there is more dimerization. Such a difference between electrode and chemical reactions should be kept in mind. In special experiments, only 2% of the anion-radical of a-nitrostilbene were prepared after interruption of controlled-potential electrolysis at a platinum gauze electrode. The kept potential was just past the cathodic peak. The electrolysis was performed in the well-stirred solution of trani -a-nitrostilbene in AN. Both processes developed in this case, namely, trans-to-cis conversion and dimerization (Kraiya et al. 2004). The partial electrolysis of a-nitrostilbene resulted in redox-catalyzed equilibration of the neutral isomers. 

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