Water free energy

Acetonitrile (AN) and Water. Free energy of transfer data have been reviewed for this system by Kolthoff and Chantooni (42) although they were apparently unaware of some work of Coetzee and Campion (43) on lithium salts. Spectroscopic data are available from three sources. Stengle and co-workers (44)... 

Lipinski s upper bounds on the numbers of hydrogen bond donors and acceptors can be related to the ability of a molecule to penetrate lipid membranes. Molecules which have groups which can form hydrogen bonds, bind to water free energy will be required to displace the water as the molecule is transported across the membrane. This energy expensive process can become limiting if too many water molecules have to be removed. Only in special cases, such as that of cyclosporin [9] does internal... 

Extrapolation of the AG = /(C ) curves to the water free energy axis enable us to estimate the maximum magnitude of variations in the free energy of water caused by adsorption (AG, i,x). The AG ux value determined in accordance with this method and the data for the free surface energy calculated using Eq. (2) are listed in Table 8. The values of maximum water layers thickness (t/ " ) perturbed by the surface, calculated on the basis of the Cw " value, are also listed in Table 8. These data permit us to conclude that the free surface energy for the adsorbents studied increases in the following order ... 

H hysteresis of the polymer-water free energy of adhesion... 

The hysteresis of the polymer-water free energy of adhesion was calculated from H = y , (cos0r — cos 0 ). where ywll is the water-air interfacial tension and 0r the receding contact angle. 

It should be noted that in frozen cellular suspensions similar to suspensions of disperse adsorbents and biopolymers, a part of water is unfrozen at T<273 K. There is concentrating of the solution of low-molecular substances, presenting in intracellular liquid. Experimentally, it is difficult to divide intra- and extracellular types of unfrozen water and water affected by dissolved low-molecular compounds (e.g., saccharides). Therefore, the value of free surface energy contains some contribution due to changes in water free energy, stipulated by the presence in intracellular liquid of low-molecular substances. It could be expected that on the dependence AG(C ) such a volumetric unfrozen water will manifest predominantly as WBW. 

Because in the equation there are 2 moles of water / free energy change of formation refers to 1 mole of substance formed. [1]... 

Table 8.8 Surface properties, solubilities in water, free energies of interaction and contactable surface areas of strictly apolar and mainly apolar solutes (van Oss and Good, 1996). Prom van Oss et al (2001a).

Here, r is positive and there is thus an increased vapor pressure. In the case of water, P/ is about 1.001 if r is 10" cm, 1.011 if r is 10" cm, and 1.114 if r is 10 cm or 100 A. The effect has been verified experimentally for several liquids [20], down to radii of the order of 0.1 m, and indirect measurements have verified the Kelvin equation for R values down to about 30 A [19]. The phenomenon provides a ready explanation for the ability of vapors to supersaturate. The formation of a new liquid phase begins with small clusters that may grow or aggregate into droplets. In the absence of dust or other foreign surfaces, there will be an activation energy for the formation of these small clusters corresponding to the increased free energy due to the curvature of the surface (see Section IX-2). 

The cleaning process proceeds by one of three primary mechanisms solubilization, emulsification, and roll-up [229]. In solubilization the oily phase partitions into surfactant micelles that desorb from the solid surface and diffuse into the bulk. As mentioned above, there is a body of theoretical work on solubilization [146, 147] and numerous experimental studies by a variety of spectroscopic techniques [143-145,230]. Emulsification involves the formation and removal of an emulsion at the oil-water interface the removal step may involve hydrodynamic as well as surface chemical forces. Emulsion formation is covered in Chapter XIV. In roll-up the surfactant reduces the contact angle of the liquid soil or the surface free energy of a solid particle aiding its detachment and subsequent removal by hydrodynamic forces. Adam and Stevenson s beautiful photographs illustrate roll-up of lanoline on wood fibers [231]. In order to achieve roll-up, one requires the surface free energies for soil detachment illustrated in Fig. XIII-14 to obey... 

Figure A2.3.21 Free energy profile of the SN2 reaction Cl +CH2CI— [Cl-CHg-Cl]— CICH +Cl in the gas phase, dimethyl fonnamide and in water (from [93]).

Most characteristics of amphiphilic systems are associated with the alteration of the interfacial stnicture by the amphiphile. Addition of amphiphiles might reduce the free-energy costs by a dramatic factor (up to 10 dyn cm in the oil/water/amphiphile mixture). Adding amphiphiles to a solution or a mixture often leads to the fomiation of a microenuilsion or spatially ordered phases. In many aspects these systems can be conceived as an assembly of internal interfaces. The interfaces might separate oil and water in a ternary mixture or they might be amphiphilic bilayers in... 

A quantitative treatment of surfactant solubility has been successfully made empirically using linear free energy relationships. An important relation is that for the linear free energy of transfer of alkanes to water [23] ... 

When carbon forms four covalent bonds with halogen atoms the second quantum level on the carbon is completely filled with electrons. Most of the reactions of the Group IV tetrahalides require initial donation by a Lewis base (p. 91) (e.g. water, ammonia) which attaches initially to the tetrahalide by donation of its electron pair. Hence, although the calculated free energy of a reaction may indicate that the reaction is energetically favourable, the reaction may still not proceed. Thus we find that the tetrahalides of carbon... 

The expressions appearing in the exponents are the free energy change of the NA-water system per unit mole in the U A and A—>B conformational transitions. The terms AF p, introduced to take into account the... 

Since the net free energy change for the cycle is zero, the difference between the computable free energies for transforming L to if, when bound to protein and when dissolved in water, is equal to the difference between the measurable standard free energies of binding L and if to protein, i.e., the difference in affinity... 

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