Specific surface Gibbs free energy

A transitional zone with a certain thickness is formed between two phases when any two phases come in contact, and this transitional zone is usually called an interface. If one phase is gas, this interface is usually referred to as the surface. The surface area of unit mass packing is known as the specific surface area. According to the thermodynamic theory, in the reversible condition of constant pressure, temperature, and composite, with an increase in unit surface area, the added value of Gibbs free energy is known as the specific surface Gibbs free energy. It is also referred to as the surface free energy, expressed in J/m. ... 

Ostwald ripening is driven by the positive surface energy, the specific, per gram amount of which can be lessened with particle growth. The change in Gibbs free energy when a particle forms is composed of two terms, a bulk term and a surface term as... 

This relationship identifies the surface energy as the increment of the Gibbs free energy per unit change in area at constant temperature, pressure, and number of moles. The path-dependent variable dWs in Eq. (2.60) has been replaced by a state variable, namely, the Gibbs free energy. The energy interpretation of y has been carried to the point where it has been identified with a specific thermodynamic function. As a result, many of the relationships that apply to G also apply to y ... 

For example, if the property in Figure 7.13 was G and the dividing surface was placed so that the two shaded regions would be equal, then there would be no surface excess G The last term in Equation (30) would be zero. The Gibbs free energy is convenient to work with, however, so such a choice for x0 would not be particularly helpful. Until now we have not had any reason to identify the surface of physical phases with any specific mathematical surface. We had not, that is, until Equation (44) was reached. Now things are somewhat different. 

The formalism described above allows evaluation of the Gibbs free energy difference between specific structural states of the protein and the reference state, which is taken to be the native structure. The formalism requires access to the crystallographic structure of the protein under study so that, for each structurally defined state, the difference in hydrogen bonds, exposure of polar and apolar surfaces,... 

Since the intermolecular adsorption of Gibbs free energy, —AGa, in Eq. (48), is independent of the specific surface area and weight of the solid in the column, except for the net retention volume, Fn, in the inverse GC at infinite dilution. Therefore — AGa can be rewritten... 

The oxide surface structure and the type of adsorbent pretreatment influence the thermodynamic characteristics of interfacial water (Gibbs free energy, heat of immersion in water, activation energy of the molecular mobility, etc.). The analyzed structural and other effects cause a significant scatter in the relationship between the specific surface area and the and AH values (Figure 1.215). 

Nanosilica A-300 (5bet=285 mVg) was used as the initial material. Nanosilica was modified by hexamethyldisilazane to substitute 50% of free surface silanols for trimethylsilyl (TMS) groups. This modification reduces the specific surface area by 15% but the hydrophilic properties practically remain since the heat of immersion in water and Gibbs free energy of the interfacial water layer are close to the corresponding values for the initial silica A-300. 

In this chapter, the fundamental concepts of colloid science have been introduced. The definition of colloidal particles, those with sizes (in all directions) ranging from 1 nm to 10 pm, has been presented, and their relevance in soil science is stated. The importance of surface properties was remarked, introducing several definitions. The specific surface area is the area per unit mass the surface tension (or surface free energy) is defined as the Gibbs free energy per unit area. The surface excess of a given species is the amount (in moles per unit area) which is accumulated... 

In previous chapters, the main modes of interaction between ions and soil mineral colloids have been discussed in Chapters 4 and 5, the principles of ion-surface interactions have been laid down, and in Chapters 8 and 9, the main features of adsorption onto silicate and oxide minerals have been reviewed. As introduced in Chapter 11, two main contributions should be considered, namely, the nonelectrostatic forces composed of physical (van der Waals forces) and/or chemical (specific bonding) interactions and the electrostatic forces arising from the charged nature of both the adsorbate and the surface this is reflected in two contributions (considered independent) to the Gibbs free energy, as in Equation 11.5 ... 

Here a is the crystal-liquid specific surface free energy, is the molecular volume, and AGj. is the difference between the liquid and crystal phases of the standard Gibbs free energy per unit volume. For small departures from equilibrium this may be expressed as... 

---