. Author manuscript; available in PMC: 2011 Jan 1.

Published in final edited form as: J Chem Theory Comput. 2010;6(3):774–786. doi: 10.1021/ct900576a

Table 3.

Hydration free energy of neutral salts (in kcal/mol)^a.

	Li⁺	Na⁺	K⁺	Rb⁺	Cs⁺
F⁻	−228.5 (−229.0)	−204.3 (−203.8)	−186.6 (−186.6)	−181.7 (−181.2)	−174.5 (−173.8)
ClR⁻	−198.9 (−199.3)	−174.7 (−174.0)	−157.0 (−156.8)	−152.1 (−151.4)	−144.9 (−144.0)
Br⁻	−192.1 (−192.9)	−167.9 (−167.6)	−150.2 (−150.4)	−145.3 (−145.0)	−138.1 (−137.6)
I⁻	−183.6 (−183.9)	−159.4 (−158.7)	−141.7 (−141.5)	−136.8 (−136.1)	−129.6 (−128.7)

	Zn²⁺	Mg²⁺	Ca²⁺	Sr²⁺	Ba²⁺

F⁻	−676.2 (−696.8)	−663.2	−585.9 (−589.4)	−553.2	−526.0 (−528.1)
Cl⁻	−617.0 (−637.2)	−604.0 (−607.0)	−526.7 (−529.9)	−494.0 (−499.0)	−466.8 (−468.6)
Br⁻	−603.4 (−624.4)	−590.4 (−594.3)	−513.1 (−517.0)	−480.4 (−486.2)	−453.2 (−455.7)
I⁻	−586.4 (−606.5)	−573.4 (−576.4)	−496.1 (−499.1)	−463.4 (−468.3)	−436.2 (−437.8)

The experimental solvation free energies reported for alkali halide salts by Tissandier et al.⁷² and Klots⁸¹ (Cs⁺) are listed in parentheses for comparison. The experimental solvation free energies for salts of divalent cations were derived from the free energies of formation of the salt minus that of the gas-phase ions (in kJ/mol): $Δ G_{aq}^{0} (A^{n +} + n B^{-}) = Δ G_{f}^{0} ({AB}_{n}) - Δ G_{f}^{0} (A^{n +} (g)) - n Δ G_{f}^{0} (B^{-} (g))$ , with $Δ G_{f}^{0} (A^{n +} (g)) = Δ H_{f}^{0} (A^{n +} (g)) - T Δ S_{f}^{0} (A^{n +} (g))$ and $Δ S_{f}^{0} (A^{n +} (g)) = 108.8555 + 12.47161 n (M) - ν^{*} S (A^{*}) \pm nS (e^{-} (g))$ where M is the molar mass in grams, v* is 1/2 for anions and 1 for cations, S(A*) is the element's absolute entropy in the standard state and S(e⁻(g)) is the absolute entropy of the gaseous electron (see Ref.72 for details). The experimental thermodynamic data are taken from the Handbook of Chemistry and Physics⁹⁵ and the 1982 NBS tables.⁸⁵