Ion hydration enthalpy

The inconvenience of the convention Af//°(H+, ao) = 0 is, of course, that it does not provide absolute values of the ion hydration enthalpies—only relative numbers can be evaluated. In other words, it tells nothing about the real size of the difference between the energetics of gas-phase and solution ions. Yet given the uncertainty that still affects the value of Af/7°(H+, ao) [50], the convention is a sensible option. 

Another result of considerable interest is the fact that the total single ion hydration enthalpies AH% are nicely paralleled by the values for individual clustering steps in the gas phase, and hence even more markedly by the AH%t n values (Figs. 7 and 8). It is not at all trivial that properties brought about by an infinite number of solvent molecules should be displayed already by such small complexes. Nevertheless, the shapes of the plots for AH% and AHo,n are quite similar. 

Table 9 Single-ion Hydration Enthalpies (kJmol-1) for Metal Cations (at 298.2K)a 1 ...

Describe and explain the trend in the ion hydration enthalpies for the halide ions. See Table 8.8. 

The overall strength of interaction between a metal ion and its hydration shell, which will parallel the strength of bonding within the [M(OH2 ),]" , can be assessed from ion hydration enthalpies. The values listed in Table are based on the single ion assumption of Halliwell and Nyburg... 

Crystal field stabilization energy is a factor that contributes to the thermodynamic stability of complexes with predominantly ionic metal-ligand interactions, and also to the variation in properties of d metals and their compounds. Some of these properties are the size of di- and trivalent ions, hydration enthalpies, lattice energies, and stability of oxidation states. 

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