Titration curve exchangers

From eqns. 4.50 and 4.51 it can be seen that complex 1 is converted into complex 2 by a stronger base 2 or into complex 3 by a stronger acid 2 in other words, complexes 2 and 3 are much more stable than complex 1. Whereas reactions 4.48 and 4.49 are addition reactions, reactions 4.50 and 4.51 are exchange reactions often Lewis titrations must be carried out in completely inert solvents such as alkanes or benzene because of instability of the titrants and titrands in other media. Examples of potentiometric Lewis titration curves are given in Fig. 4.9 for CS2 and C0220, where one of their resonance structures can react as a Lewis acid with OH as a Lewis base ... 

The pH dependence of could be due to changes in A-B loop disorder rates, perhaps the chemical exchange phenomenon observed for NPl-ImH (Section ll,E,2,b), or to changes in ligand bond strength. The change in lies in the off-rates (Tables I-Ill) consistent with the loop disorder model. Plots of vs pH display an excellent fit with the equation for a titration curve (Fig. 21), indicating that the transition... 

The experimental procedures of BET, TGA, and XRD have been described in detail elsewhere [8]. The interlayer d-spacing from XRD pattern is determined by the angle of ((X)l) reflection. For the measurement of ion-exchange capacity, SO mg of sample was suspended with 10 cm of NaCl solution (0.1 N), and the pH values were measured with addition of NaOH solution (0.1 N) to obtain the potentiometric titration curve at rocnn temperature. 

To mimic c T-[(NH3)2Pt(H20)2]2+ with the more rapidly exchanging Pd11 and to prevent isomerization, it is necessary to employ the complex of ethylenediamine (en), [(en)Pd(H20)2]2+, that through chelation is necessarily cis. Upon titration with standard base an endpoint is reached after the addition of only one equivalent of base at pH 7.5, but the reversible titration curve is flattened on the pH axis and cannot be fitted with the equilibrium expression for a simple deprotonation. It was proposed that the mono-hydroxo complex dimerizes to abinuclear dihydroxo-bridged dimer [9], The two reactions and their equilibrium constant expressions follow. 

Ternary cation exchange, 216 Tetrahedral coordination, 102 Titration curves, 27-29, 154-159 Equivalence points, 28-29 pH-bufifering, 86-88 Acid clays and soils, 154-160 Total dissolved solids (TDS), 479, 491 Toxicity, 484 Indicators, 484 Ceriodaphnia, 484 Water fleas, 484 TIEs, 484 Metals, 484 Hard- metals, 12 Soft-metals, 12 Triazines, 345, 357 Trioctahedral silicates, 121... 

Back-titrations of the reaction solutions were also performed. The back titrant was O.OIN HCl solution. The shapes of the titration curves were similar for both the forward and back titrations. The number of milliequivalents added to reach the equivalence points was different for each titration pair. In the back titrations, the exchange capacities of the molecules were slightly smaller. The smaller exchange capacities can be explained by irreversible colloid formation. These colloids would remove some of the exchange sites from contact with the solution. A titration curve for K" " shows the two sites prevalent in the Na" series. The first site s pK differs from its Na" " analog by 0.7 units. The second site s pK is essentially the same as the Na" counterpart. This indicates that the lower pK... 

Figure 1. Titration curves for monovalent cation-hydrogen exchange. (A) Na at 0.11 (B) Na at 0.3 I (C)Na at 0.5 I (D) K" at 0.11. Every third data point is shown. Interpolation is by a cubic spline method.

Figure 10 The pH titration curves (top) and dependence of alkali metal ion uptake on pH (bottom). Exchanger, 0.10 g total volume, 10.0 cm temp., 30°C, ionic strength, 0.1 (MNO3 + HNO3) or (MNO3 -I- MOH), M = Li, Na, K, Rb, and Cs. (From R. Chitrakar and M. Abe, Solvent Extr. Ion Excb.,7-n2 (1989). With permission.)...

Four types of hydrous antimony oxide (antimonic acid), the amorphous (A-SbA), the glassy (G-SbA), the cubic (C-SbA), and the monoclinic (M-SbA) are known so far [138]. Both the A-SbA and G-SbA affect the selectivity sequence Li" < Na" < K" " < Rb+ < Cs", while the selectivity sequence of C-SbA is unusual with Li" " K+ < Cs < Rb" Na" " for micro amounts in acid media (Fig. 19). The degree of crystallinity of a-ZrP strongly influences its ion-exchange behavior as mentioned earlier. The pH versus base added plots for a-ZrP with different crystallinity are shown in Fig. 13. It is seen that each increase in acid concentration at a fixed reflux time is reflected in the shape of the curves. The titration curves with the most well-defined plateaus were obtained with the most highly crystalline samples [126]. 

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