Hydration of ions

The nearness of ehai aeter of the physieal fields aetion on substanees has been established. Use of the wide speetmm of frequeneies, intensities and time of physieal aetion had allowed to reeeive the maximum analytieal effeet. In many eases not only intensifieation of mass transfer but also a ehange of solution stmeture, hydration of ions, their reaetion eapability, mpture of polymer bounds, and formation of free radieals take plaee. 

The internal structure of a liquid at a temperature near its freezing point has been discussed in Sec. 24. Each molecule vibrates in a little cage or cell, whose boundaries are provided by the adjacent molecules, as in Fig. 20, and likewise for each solute particle in solution in a solvent near its freezing point. It is clear that the question of the hydration of ions no longer arises in its original form. In aqueous solution an atomic ion will never be in contact with less than three or four water molecules, which in turn will be in contact with other water molecules, and so on. There is an electrostatic attraction, not only between the ion and the molecular dipoles in immediate contact with it, but also between the ion and molecular dipoles that are not in contact with it. For solvent dipoles that are in contact with a small doubly charged ion, such as Ca++,... 

Fig. 17-13. Hydration of ions orientation of water dipoles around ions in aqueous solutions.

Morris DFC (1968/1969) An Appendix to Structure and Bonding. 4 6 157-159 Morris DFC (1968) Ionic Radii and Enthalpies of Hydration of Ions. 4 63-82 Mortensen OS (1987) A Noncommuting-Generator Approach to Molecular Symmetry. 68 1-28... 

In almost all theoretical studies of AGf , it is postulated or tacitly understood that when an ion is transferred across the 0/W interface, it strips off solvated molecules completely, and hence the crystal ionic radius is usually employed for the calculation of AGfr°. Although Abraham and Liszi [17], in considering the transfer between mutually saturated solvents, were aware of the effects of hydration of ions in organic solvents in which water is quite soluble (e.g., 1-octanol, 1-pentanol, and methylisobutyl ketone), they concluded that in solvents such as NB andl,2-DCE, the solubility of water is rather small and most ions in the water-saturated solvent exist as unhydrated entities. However, even a water-immiscible organic solvent such as NB dissolves a considerable amount of water (e.g., ca. 170mM H2O in NB). In such a medium, hydrophilic ions such as Li, Na, Ca, Ba, CH, and Br are selectively solvated by water. This phenomenon has become apparent since at least 1968 by solvent extraction studies with the Karl-Fischer method [35 5]. Rais et al. [35] and Iwachido and coworkers [36-39] determined hydration numbers, i.e., the number of coextracted water molecules, for alkali and alkaline earth metal... 

Figure 6.2 (A) Hydration of ions (B)-(D) ionization phenomenon for HCI acid...

Samoilov, O. Ya., Structure of Aqueous Electrolyte Solutions and Hydration of Ions, Consultants Bureau, New York, 1965. 

Yatsimirskii, K.B. "Thermochemical Radii and Heats of Hydration of Ions," Izvest. Akad. Nauk, S.S.S.R., Otdel. 

As already treated in the hydrogen section, isotope fractionations, the hydration of ions may play a significant role in hydrothermal solutions and volcanic vapors (Driesner and Seward 2000). Such isotope salt effects may change the oxygen isotope fractionation between water and other phases by several permil. 

K. Fajans opened the field of study of heats of hydration of ions. In 1919 62) he not only provided the definition of the new quantity and equation (1) but he attempted to derive values for the absolute enthalpies of hydration of individual ions approximately —260 kcal mole i was his estimate for A subsequent paper on the subject 63) was published in 1921. Unfortunately this is not quoted in recent reviews but it lists values for iyM+ and Wx which are quite remarkably similar in magnitude to those given in Table 7. 

Ionic Radii and Ethalpies of Hydration of Ions. An Appendix to Structure and Bonding Vol. 4 (1968) D. F. C. Morris- 157... 

This chapter consists of a description of the structure of liquid water and the nature of ions in aqueous solution. The discussion is largely restricted to the interactions between monatomic ions with liquid water in which they become hydrated by acquiring a hydratiun sphere or shell-Additionally, a few diatomic and polyatomic anions are dealt with, including the important hydroxide ion. The hydration of ions derived from the s- and p-block elements of the Periodic Table, and the derivation of values of their enthalpies and entropies of liydralioii, are described in considerable detail. 

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