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Ionic volumes estimation

The volume occupied by the atoms has been calculated as follows. First, the number of each type of atoms per gram of zeolite has been determined. After that, the number of atoms has been multiplied by its atomic volume estimated from the ionic radius and assuming spherical geometry. In the case of the exchanged zeolites, i.e. zeolites CaY, SrY and BaY, the residual Na content has also been taken into account. Equation 3 has been used for this purpose. [Pg.491]

The authors have estimated the intracrystalline volume of clinoptilolite from the water content of the Na form and conclude from their estimates of the ionic volumes of the organic cations used that 100% exchange is theoretically possible for all ions. They conclude from a consideration of the heulandite structure (41), which is isostructural with clinoptilolite, that partial ion sieving occurs because there are 2 different networks of channels that intersect. Diffusion into and through one network is via rings of 10 tetrahedra having a planar projection that... [Pg.370]

If the surface sodium ions in a soda-lime-silica glass are ion-exchanged with potassium ions, estimate the surface stress. Assume the exchange is performed below the glass transition temperature and the percentage ionic volume increase is estimated to be 4.2% (sodium to potassium). [Pg.314]

Despite this drawback there is an interest in science and technology in single-ion quantities for rationalizing the discussion of electrolyte solution properties. Various methods have been developed for their estimation based on extrathermodynamic assumptions, such as the following (1) The contributions of cation and anion are set equal for a salt composed of ions of equal charge and approximately equal radii (2) the results of measurements on a series of homologous electrolytes are extrapolated with regard to ionic radii or ionic volumes to zero ion size or zero reciprocal radii (3) the differences in conventional ionic properties are used for theoretically rationalized extrapolations and (4) the properties of ions are compared with those of isoelectronic neutral molecules of similar chemical constitution and size. [Pg.82]

Following Gardas and Coutinho [297], the temperature dependence of the ionic volumes of RTlLs at ambient pressures is estimated, as ... [Pg.160]

Properties of Different Solvents. In discussing molecular dipoles in Sec. 25, we estimated the force of attraction between an atomic ion and a dipole having the most favorable orientation and found this attraction to be very strong. In any ionic co-sphere those molecular dipoles which have a favorable orientation will bo attracted, while those that have the opposite orientation will be repelled. Since the former are more numerous the solvent in the co-sphere is, on the whole, attracted toward the ion. Since the liquid is not incompressible, we must expect that this will lead to a contraction in each co-sphere. In any ionic solution the sum of the contractions that have taken place in the co-spheres of the positive and negative ions will be apparent if we measure accurately the volume of the solution. [Pg.186]

We set out with the idea that, in the vicinity of each ion in solution there is likely to be a certain amount of electrostriction—a certain shrinkage of the solvent caused by the attraction between the ionic charge and the polar molecules. In order to estimate from experimental data how much shrinkage, if any, has taken place, we must start with a correct idea of what would have been the volume of the solution, if no shrinkage had taken place. In making a comparative study of various solutes, we need a common basis for comparison. Since this is not provided by the volumes of the crystalline solids, we may try a different approach. We may compare the addition of any pair of ions to the solvent with the addition of a pair of solvent molecules. [Pg.190]

The major surfactant families in use in the European market in volume terms are the non-ionics followed by anionic derivatives. A detailed breakdown of the total surfactant consumption for Western Europe can be found in Tables 1.6 and 1.7, which show the estimated proportions for the various uses of surfactants in the European market. Probably the most important final use of surfactants in Europe is in detergent manufacture, as demonstrated by the figures summarised in Table 1.8. [Pg.40]

The rate constants for the reaction of N-dodecyl-3-carbamoyl-pyridinlum ion with cyanide in both cationic and nonionic o/w microemulsions have been measured as a function of phase volume. Added salt has no effect in the cationic system, but the rate constants in the nonionic system depend upon ionic strength as would be expected for a reaction between two ions. In order to compare the two microemulsions, the ionic strength in the reaction region has been estimated using thicknesses of 2-4A. The former produces values of the effective surface potential which yield... [Pg.184]

The above speculation [21] may be extended to include the related quaternary ammonium compounds such as xylocholine (XXXIX). It is probable that the volumes of the guanidinium ion and the trimethylammonium group are similar. The ionic radius of the guanidinium ion (IX) is about 3A the ionic radius of the tetramethylammonium ion has been estimated [300] to be 3-4A, although rather smaller values have also been proposed [301-303]. Crystallographic analyses of muscarine iodide [304], choline chloride [305] and acetylcholine bromide [306] have revealed that the carbon to nitrogen distance is about l-SA, and that a hydrogen bond (C-H-0 distance 2-87-3 07A) exists in the crystals of these compounds. [Pg.173]

From Fe—O distances in Fe " aq and Fe " aq ionic radii for the bare ions have been calculated (0.72 A and 0.64 A, respectively) and compared with established crystal radii. " Theoretical calculations on the aqua-cations have estimated the effects of the (7-electrons through optimization of geometry and energy minimization. " SCF calculations for [Fe(H20)J ", forx = 5, 6, and 7, and n = 2 and 3, have been coupled with measured activation volumes, A, for water exchange to give insight into the mechanisms involved. Such considerations, complemented by consideration of measured AG and AH, are... [Pg.484]

When mixed micelles are used, in contrast to simple micelles, a much stronger alteration of the ionic mobility of these micellar vehicles is caused by the higher increase in volume/radius and the reduction of the charge. This means that an estimation of A/x directly from the electropherogram without marking the mixed micelle is no longer possible. [Pg.127]


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See also in sourсe #XX -- [ Pg.313 ]




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Ionic volume

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