Entropies of Transfer

As indicated in the previous section, the derivation of Gibbs free energies of transfer, and thence of entropies of transfer, from trichloride... 

Tab. 2.6 Standard Gibbs energies, enthalpies, and entropies of transfer of ions from water to non-aqueous solvents (25 °C)1 ...

We shall discuss now the variation of the three main thermodynamic functions with solvent composition for the case of n-Bu4NBr-water-acetone system and shall extend this discussion to the n-Bu4NBr-water-THF system. Figure 4 and Table IV present the results obtained. The figure was constructed as follows first the standard enthalpy of transfer AH°t, obtained by Ahluwalia and co-workers (12) from pure water to Z2 = 0.30, was used in order to get the standard entropy of transfer function from the relation ... 

Table IV. Standard Free Energy, Enthalpy, and Entropy of Transfer of n-Bu4NBr from Water to Water—Acetone Mixtures at 298.15°K...

Table 3.4 Air-Hexadecane, Air-Water, and Hexadecane-Water Equilibrium Partitioning of Hexane, Benzene, Diethylether, and Ethanol Free Energies, Enthalpies, and Entropies of Transfer, as well as Partition Constants Expressed on a Molar Base (i.e., mol U phase 1/mol L/ phase 2)...

ENTROPIES OF TRANSFER (ON THE MOLAR SCALE) FROM METHANOL TO AQUEOUS METHANOL OF TETRAETHYLTIN, MERCURIC CHLORIDE, AND THE TETRAETHYLTIN— MERCURIC CHLORIDE TRANSITION STATE (cal.mole- .deg- ) AT 298 °KJ ... 

ENTROPIES OF TRANSFER (ON THE MOLAR SCALE) FROM METHANOL TO WATER OF... 

Hefter, G., Marcus, Y., and Waghome, W. E. (2002) Enthalpies and entropies of transfer of electrolytes and ions from water to mixed aqueous organic solvents, Chem. Rev. 102, 2773-2835 and references cited therein. 

Solubility, Gibbs Energy, and Entropy of Transfer of Hydrocarbons from the Uquid Phase to Water ... 

Bearing this in mind, it is clear from Fig. 11 that the entropy of transfer of all nonpolar molecules from the liquid phase to water becomes equal to zero in a rather limited temperature range T 130-160°C. This important behavior was noticed first by Baldwin (1987), who assumed that the heat capacity increment was temperature independent. However, as illustrated in Fig. 12 for liquid benzene and pentane, the temperature depen-... 

An immediate consequence of the fact that the entropy of transfer of all nonpolar substances into water at 7s is zero is a clear proportionality between the entropy of solution at 25°C and the surface area of the solute (see Tables IV and V). Indeed, if as noted, the heat capacity increment of the transfer of a nonpolar molecule into water is proportional to Ns and is a universal function of temperature, one can expect, according to Eq. (5), that the entropy of transfer should also be proportional to Ns at any temperature T if it is zero at some temperature Ts. 

Entropies of transfer, 5AStr, are available from relationship (2). 

Enthalpies and Entropies of Transfer of Ions from Water to Non-aqueous... 

Table 4 Standard Free Energies, Enthalpies, and Entropies of Transfer of Singly Charged Ions from Water to Dipolar Aprotic Solvents (kcal moD1)... 

The coupling phenomenon may be described in terms of the entropy of transfer S which is the entropy transferred by a unit flow of substance under conditions of uniform temperature, and defined by... 

This relation represents the Thomson heat with specific entropies of transfer of individual metals a and b... 

Alot of information about the free energies of transfer of single ions between pure solvents has been accumulated. Less numerous are determinations in mixed solvents, and the ionic enthalpies of transfer and entropies of transfer as function of mole fraction are known as an exception only. In Table 1 ions and solvent mixtures are listed for which free energies of transfer and some other thermodynamic quantities have been determined. 

Here EgEn° and BEN° are the standard potentials of the Ag-AgI electrode in ethylene glycol and the solvent on the mole-fraction scale. The standard entropy of transfer, ASt°, was calculated from... 

The differences in the hydration of a solnte in H2O and D2O have been extensively stndied by measnring their thermodynamic properties, the change of free energy (AG°t), enthalpy (A//°t), and entropy (AY°t) at the transfer of 1 mol of solnte from a highly dilute solution in H2O to the same concentration in D2O under reversible conditions (mostly 25 °C and atmospheric pressure). Greyson measured the electromotive force (emf) of electrochemical cells of several alkali halides containing heavy and normal water solutions. The cell potentials had been combined with available heat of solution data to determine the entropy of transfer of the salts between the isotopic solvents. The thermodynamic properties for the transfer from H2O to D2O and the solubilities of alkali halides at 25° in H2O and D2O are shown in Table 4. 

Exceptions are those for Li and Na+ in NM, and Li+ in PC and TMS. It follows that the interaction of these monoatomic monovalent cations is more exothermic with most polar solvents than with water. On the other hand, the enthalpy of transfer of the smaller anions, CP and Br, is almost always positive. This is a direct indication that these species are difficult to dissolve, especially in aprotic solvents. In the case of P and CIO4, the enthalpy of transfer is usually negative. Comparison of the enthalpy data with the Gibbs energy data recorded in tables 4.6 and 4.7 shows that these quantities are very different. When both Gibbs energies and enthalpies of transfer are available, one can calculate the entropy of transfer [39]. 

Two main sources of entropy may have been suggested. The first is related to the so-called hydrophobic effect, which was initially established from a consideration of the free energy enthalpy and entropy of transfer of hydrocarbon from water to a liquid hydrocarbon. Some results are listed in Table 3.4 this table also includes the heat capacity change ACp on transfer from water to a hydrocarbon, as well as that is the heat capacity in the gas phase. It can be seen from the... 

The entropies of transfer are positive at 298.15 K. Neither the enthalpy nor the entropy of transfer appears to be a linear function of the number of carbon atoms. The methylene group contribution is not constant, but depends on the alcohol chain length. DeLisi and Milioto have tried to explain this by taking the size of the solute into consideration. The solubilization of additives in the micelles thus involves a micellar rearrangement to accommodate the alkyl chain. In principle, short-chain alcohols, mostly accommodated in the palisade layer, need less rearrangement of the micelle than the longer-chain alcohols that will require a cavity suitable to accommodate part of the alkyl chain. 

It is generally accepted that the hydrophobicity of alcohols is enhanced when the hydrogenated alkyl chain is fluorinated. Only a few such systems have been studied,but it appears that AG is more negative for the fluorinated alcohols, whereas the enthalpies and entropies of transfer are more positive. The effect on TAS is larger than that on AH. It thus seems that the difference between the hydrogenated and fluorinated alcohols largely stems from a more pronounced hydro-phobic effect of the fluorinated chain in the aqueous phase, and is not an effect of a larger affinity toward the micelles. 

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