Gibbs free energy of hydration

It must be noted here that, because there are 16 melt components in the model, there should be 120 binary interaction parameters. Only 55 of these are hsted in table 6.15, because the remaining ones are considered virtually equal to zero. Lastly, it must be noted that the Gibbs free energy of hydrated magmas cannot be obtained simply by apphcation of equations 6.78 to 6.85, but requires additional considerations that cannot be outlined in this context (see Ghiorso and Carmichael, 1980, and Ghiorso et al., 1983, for detailed treatment of the method). 

These differences stimulated our interest and prompted us to study the effects of solvation on (R,R )-tartaric acid amides. Encouraged by the widespread usage ofAMSOL [42] (vide infra) we decided to use it to calculate Gibbs free energies of hydratation. We performed the calculations with the use of the solvation model SM5.4 [43-46] and hamiltonian PM3 [47] for all structures, optimized at the RHF/6-31G level [20],... 

TABLE 21.6 Enthalpies, entropies, and Gibbs free energy of hydration for sulfuric acid dimer calculated at T = 298.15 K and P = 101.3 kPa. Abbrevi- ... 

As discussed later in this chapter, metal ion partitioning appears to be governed by the interactions of the ions with water. Predictive tools are being developed [23] utilizing such thermodynamic parameters as an ion s Gibbs free energy of hydration (AGhyj). 

Table 3 Gibbs Free Energies of Hydration" for Representative Ions...

The Gibbs free energy of hydration (or, qualitatively, an even simpler guide charge-to-size ratio) can be used to predict the relative ordering of distribution ratios for chaotropic ions in a given ABS. A linear relationship was observed for the D values of TcO]", 1 , and Cl" at three different... 

Gibbs Free Energy of Hydration of Metal Cation) kj/mol... 

T. Z. M. Denti, T. C. Beutle W. F. van Gunsteren, and F. Diederich, /. Phys. Chem., 100, 4256 (1996). Computation of Gibbs Free Energies of Hydration for Simple Aromatic Molecules A Comparative Study Using Monte Carlo and Molecular Dynamics Computer Simulation Techniques. 

Marcus Y (1991) The thermodynamics of solvation of ions, part 5. The Gibbs free energy of hydration of ions at 298.15 K. J Chem Soc Faraday Trans 87 2995-2997 Marcus Y (1994) Viscosity B-coefficients, structural entropies and heat capacities, and the effect of... 

The CPCM/HF/6-31G(d) (Radii-UAHI //CPCM/HF/6-31l4G(d,p) and Monte Carlo QM/MM levels of theory were the most accurate and produced Gibbs free energies of hydration within 0.4 kcal/mol of expaimental values [117]. 

Results from self-consistent field (SCF) molecular orbital calculations, in combination with gas-phase photoelectron data and results from post-SCF calculations have provided a basis for descriptions of the valence electronic structure of gas-phase nucleotides and of nucleotides in water-counterion clusters. These descriptions contain values for 11 to 14 of the lowest energy ionization events in the DNA nucleotides 5 -dGMP , 5 -dAMP, 5 -dCMP and 5 -dTMP . When used with an evaluation of the difference between the Gibbs free energies of hydration for the initial and final states associated with ionization, this approach also describes the influence of hydration on the energetic ordering of ionization events in nucleotides. 

Gibbs free energies of hydration, before and after ionization (AG y/l) and AGhyj(2)) were obtained by employing the Langevin dipole relaxation method (45-47) incorporated in the Polaris 3.2 program (46). Before and after ionization, solvent relaxation is modelled by evaluating the relaxation of discrete dipoles distributed on a lattice... 

The approximated surface calculation (ASC) procedure calculates partial atomic van der Waals surface areas through an analytical method (Ulmscheider and Penigault 1999a) and then the Gibbs free energy of hydration is calculated by considering it to be an additive property. The ASC procedure considers the hybridization state of the atoms. 

The Gibbs free energy of hydration, AGx(aq), was calculated using the MC simulation coupled to the thermodynamic perturbation theory (TPT) [41-43], in which a series of MC runs is carried out. A system with one solute molecule and 1000 water molecules at normal conditions in the NpT ensemble was used for the TPT calculations. The... 

Table 6 Non-electrostatic and electrostatic contributions to the Gibbs free energy of hydration, Gj[oq), the total hydration free energy, AAG c, v(aq), and the Gibbs free energy change in aqueous solution.

Govindarajan R, Perumalsamy M (2013) Phase equilibrium of PEG 2000 + triammonium citrate + water system relating PEG molecular weight, cation, anion with effective excluded volume, Gibbs free energy of hydration, size of cation, and type of anion at (298.15,308.15, and 318.15) K. J Chem Eng Data 58 2952-2958... 

In water solution, as shown by AMSOL calculations, the conformational preferences of the studied amides show up. Gibbs free energies of hydratation calculated witii tile SMS.4 model and PM3 hamiltonian for stmctures optimized at the RHF/6-3 1G level indicated tiiat those most favored by hydratation are the T- and G-conformers for tiie diamide and N,N,N ,N -tetramethyldiamide of (R, R)-tartaric acid, respectively. 

See for example Kollmann, P. Free energy calculations applications to chemical and biochemical phenomena, Chem. Revs. 1993,93,2395-2417 Mordasini Denti, T. Z. Beutler, T. C. van Gunsteren, W. F. Diederich, F. Computation of Gibbs free energies of hydration of simple aromatic molecules a comparative study using Monte Carlo and Molecular Dynamics computer simulation techniques, J. Phys. Chem. 1996,100,4256-4260. 

Table 6.8 lists the calculated Gibbs free energies of hydration for lanthanide(in) ions. The LPPMP2 calculated results agree very well with the experimental data [126,127],... 

Using DFT and MP2 combined with LPPs, the Gibbs free energies of hydration for actinide(ni) ions have been calculated by Wiebke and coworkers [129] (see Table 6.10). It can be seen that the single-point corrected LPP MP2 results are about 152 kJ/mol lower than the LPP DFT/BP86 results. There are only two experimental values available, i.e., -3205 kJ/mol for U and -3235 kJ/mol for Pu [137]. Compared to LPP MP2 results, the experimental data are by 41 and 6 kJ/mol lower for U and Pu, respectively. The differences between the AG obtained from a model by David and Vokhmin [138] and the DFT calculated results are very significant, i.e., the deviations amount up to 338 (Lr) and 238 kJ/mol... 

Y. Marcus, Thermodynamics of solvation of ions. Part 5.- Gibbs free energy of hydration at 298.15 K, J. Chem. Soc. Faraday Trans., 87, 2995-2999 (1991). 

Fig. 14. Charge displacements of different anions and cations on a PC (phosphatidylcholine) and a Mono (monoolein) membrane. The open circle indicates the reference ions Na or Ci. Ions are ciassified according to their Gibbs free energies of hydration AGiiyd- (After Garcia-Ceima...

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