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xx CONTENTS

2.15.3. Do Oppositely Charged Ions of Equal Radii Have Equal Heats of
Solvation? .................................. 101
2.15.4. The Water Molecule as an Electrical Quadrupole ............. 102
2.15.5. The Ion–Quadrupole Model of Ion–Solvent Interactions ......... 103
2.15.6. Ion-Induced Dipole Interactions in the Primary Solvation Sheath .... 106
2.15.7. How Good Is the Ion–Quadrupole Theory of Solvation? ......... 107
2.15.8. How Can Temperature Coefficients of Reversible Cells Be Used to
Obtain Ionic Entropies?.................................... 110
2.15.9. Individual Ionic Properties: A Summary .................. 114
2.15.10. Model Calculations of Hydration Heats .................. 114
2.15.11. Heat Changes Accompanying Hydration...................... 117
2.15.11.1. .............. ................. 119
2.15.11.2. ............................... 120
2.15.11.3. .............. .................... 121
2.15.11.4. ................................... 121
2.15.11.5. (Model A) ....................... 121
2.15.11.6. (Model B) ....................... 122
2.15.11.7. (Model C) ....................... 122
2.15.11.8. ......................................... 124
2.15.11.9. Numerical Evaluation of .................. 124
2.15.12. Entropy of Hydration: Some Possible Models ............... 126
2.15.13. Entropy Changes Accompanying Hydration ................ 126
2.15.13.1. ...................................... 127
2.15.13.2. ..................................... 127
2.15.13.3. ...................................... 127
2.15.13.4. ....................................... 130
2.15.13.5. .................................... 132
2.15.13.6. (Model A) ......................... 133
2.15.13.7. (Model C) ......................... 134
2.15.14. Is There a Connection between the Entropy of Solvation and the Heats of
Hydration? ................................. 138
2.15.15. Krestov’s Separation of Ion and Solvent Effects in Ion Hydration .... 139
2.16. More on Solvation Numbers ...................... 139
2.16.1. Introduction ................................. 139
2.16.2. Dynamic Properties of Water and Their Effect on Hydration Numbers . . 141
2.16.3. A Reconsideration of the Methods for Determining the Primary
Hydration Numbers Presented in Section 2.15 ............... 142
2.16.4. Why Do Hydration Heats of Transition-Metal Ions Vary Irregularly with
Atomic Number? ................................... 145
Further Reading .................................. 152
2.17. Computer-Simulation Approaches to Ionic Solvation ...... 153
2.17.1. General ................................... 153
2.17.2. An Early Molecular Dynamics Attempt at Calculating Solvation Number 154
2.17.3. Computational Approaches to Ionic Solvation ............... 154
2.17.4. Basic Equations Used in Molecular Dynamics Calculations ........ 155