Debye charging process

Describe the difference between the Guntelberg and Debye charging processes. Which process should be more effective in deriving an equation for the activity coefficient ... 

The electric part Eei of the free energy of double-layer interaction (Eq. (5.4)) can be expressed in a different way on the basis of the Debye charging process in which all the ions and the particles are charged simultaneously from zero to their full charge. Let /I be a parameter that expresses a stage of the charging process and varies from 0 to 1. Then F x can be expressed by... 

In the next section we shall derive the same expression (6.12.94) by a different charging process, known as the Debye charging process. 

Now, the Guntelberg charging process was suggested several years after Debye and Htickel made their theoretical calculation of the activity coefficient. These authors... 

Another and possibly more convincing charging process has been used by P. Debye. Physik. Z t 25, 97 (1924), and consists in charging all the tons simultaneously by a given fraction of their total charge. 

While the Debye-Huckel derivation was based on a charging process which took into account the distance of closest approach, a, the kinetic effect of the hard core could not adequately be dealt with. In order to include these effects. Pitzer proposed using the osmotic pressure equation (PI) ... 

We will not discuss the details of the Debye-Huckel theory. The main idea of the theory was to pretend that the ions in a solution could have their charges varied reversibly from zero to their actual values. This charging process created an ion atmosphere around a given ion with an excess of ions of the opposite charge. The reversible net work of creating the ion atmosphere was calculated from electrostatic theory. According to Eq. (4.1-32) the reversible net work is equal to AG, which leads to equations for the electrostatic contribution to the chemical potential and the activity coefficient for the central ion. The principal result of the Debye-Hiickel theory is a formula for the activity coefficient of ions of type i ... 

According to Eq. (19), t, is the time scale for excited state solvation for a Debye solvent. In fact, it is the time scale for both excited state and ground solvation of dipolar solutes and ionic solutes, t, also plays a role in a broad range of reactive (Section III) and nonreactive charge transfer processes in solution. It is clearly worthwhile to establish a physical picture for this important variable. 

The primary particle involved in the screening process is the mobile electron. One has then the problem of a self-consistent calculation of the charge distribution in the neighborhood of a test charge. The Thomas-Fermi approach to this problem is the analog of the Debye-Huckel calculation wherein allowance has been made for the Pauli exclusion principle. From any standard text one can obtain the Poisson equation (19)... 

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