Exchange involving

Both the kinetics and the equilibrium aspects of ion exchange involve more than purely surface chemical considerations. Thus, the formal expression for the exchange... 

To accomplish any separation of two cations (or two anions) of the same net charge, the stationary phase must show a preference for one more than the other. No variation in the eluant concentration will improve the separation. However, if the exchange involves ions of different net charges, the separation factor does depend on the eluant concentration. The more dilute the counterion concentration in the eluant, the more selective the exchange becomes for polyvalent ions. 

Table 7-20 shows the computer results using an external heat exchanger involving a non-isothermal cooling medium. 

The quantitative formulation of chemical exchange involves modification of the Bloch equations making use of Eq. (4-67). We will merely develop a qualitative view of the result." We adopt a coordinate system that is rotating about the applied field Hq in the same direction as the precessing magnetization vector. Let and Vb be the Larmor precessional frequencies of the nucleus in sites A and B. Eor simplicity we set ta = tb- As the frequency Vq of the rotating frame of reference we choose the average of Va and Vb, thus. 

Another exchange involves Zn or Cd metal in a polar solvent, such as THF or diglymc ... 

Sutin et al have recently re-examined the pathways of exchange involving chloride and have evaluated the rate coefficients as k- = 57.6 and k = 159 1. mole . sec at 25 °C and n = 3.0 M. These workers have pointed out that step with coefficient k can occur in two ways... 

There are large cations in these cells, e.g., tetra-alkylammonium cations in the organic phase and the interfacial ion exchange involves only so-called critical ions, here X and LX ions are practically not transferred through the organic phase. Both liquid interfaces are reversible with respect to the appropriate anion, X or L. EMF is, in practice, also influenced by the diffusion potential in the organic phase, and in the case of cells of the type in Scheme 11 - by the difference of standard transfer energies of both ions (Section III.A)... 

The carbon atoms which are involved in the short intermolecular contacts between molecules (less than 4A 02/C14 and 01/C4, C5, C6, Figure 7) carry a significant spin density. The magnetic molecular orbitals of the corresponding oxygen atoms (01 and 02) are twisted and hybridized. Thus we have evidence that the intermolecular exchange involves these contacts. 

If the heat exchange involves desuperheating as well as condensation, then the exchanger can be divided into zones with linear temperature-enthalpy profiles in each zone. Figure 15.12a illustrates desuperheating and condensation on the shell-side of a horizontal condenser. The total heat transfer area is the sum of the values for each zone ... 

Optimal solution for a heat exchanger involving discrete variables... 

Rather small selectivity differences are observed for homovalent-and heterovalent exchanges involving alkali, alkaline earth, bivalent transition metal ions, aluminium and rare earth cations, as is amply evidenced from the extensive compilation by Bruggenwert and Kamphorst (16). This compilation includes various clay minerals illite, montmorillonite, vermiculite and kaolinlte. 

In general, the (scarce) thermodynamic data for exchanges involving complexes leads us to conclude that the selectivity enhancement upon complexing is enthalpy driven and may be ascribed to enhanced charge dependent (primarily coulombic) interactions with the surface as compared with the aqueous ions. 

Drs. Stanbury and Taube [Stanbury, D. M. Mulac, W. A. Sullivan, J. D. Taube, H. Inorg. Chem. 1980, 19, 3735] have also commented on the Demas study. They have used a rate constant for the self-exchange involving to ca cu ate he... 

When ion exchange involves ions of different mobilities, the rate depends also on the relative positions of the ions. If the more mobile ion is diffusing out of the resin, the rate will be greater than if it is diffusing into the resin, when pellet-diffusion controls. 

The AC values for muonium hydrogen isotope effects are listed in Table 2.1. The AAC value obtained for LiH, H2 isotopic exchange involving Mu-H is 92 cm-1,... 

Flo. 27. Geometrical relationships for a possible dissociative mechanism of exchange involving an allylio intermediate. 

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