Electrolytes, ionogenic

It was found in later work that it is precisely the idea of ionic hydration that is able to explain the physical nature of electrolytic dissociation. The energy of interaction between the solvent molecules and the ions that are formed is high enough to break up the lattices of ionophors or the chemical bonds in ionogens (for more details, see Section 7.2). The significance of ionic hydration for the dissociation of electrolytes had first been pointed out by Ivan A. Kablukov in 1891. 

Electrolyte concentration and pH have profound effect on electrostatic interactions and consequently on the retention behavior of ionogenic sample components in RPC. In agreement with the results of a detailed theoretical treatment (207), which is summarized in Section V,B,2,b. ionization results in a decrease of the retention factor although exceptions... 

Electrolytes are classified into ionophores and ionogens. Ionogens (like hydrogen halides) exist as neutral molecules in their... 

Analyzing the conductance data for sodium in NH8 solutions led to the original mass action equilibria postulate of Kraus (27). It was originally proposed that metal in NH8 solutions behave as weak electrolytes or ionogens, producing metal ions and solvated electrons in accord with the equation... 

Some equations of the reaction with water of a few ionogenic electrolytes are given below the reactions of molecular acids and bases were discussed in the previous paragraph. 

In many colloidal systems, the double layer is created by the adsorption of potential-determining ions for example, the potential 0o the surface of a /Silver iodide particle depends on the concentration of silver (and iodide) ions in solution. Addition of inert electrolyte increases k and results in a corresponding increase of surface charge density caused by the adsorption of sufficient potential-determining silver (or iodide) ions to keep 0O approximately constant. In contrast, however, the charge density at an ionogenic surface remains constant on addition of inert electrolyte (provided that the extent of ionisation is unaffected) and 0O decreases. 

There are some cases where a reaction, that is, the formation or dissolution of a chemical bond, is involved along with ion exchange phenomena (Helfferich, 1983). Examples of this are acid-base neutralization, dissociation of weak electrolytes in solution or weak ionogenic groups in ion exchangers, complex formation, or combinations of these (Table 5.2). With some of these, very low apparent D in ion exchangers have been noted. 

Solutions of non-electrolytes contain neutral molecules or atoms and are nonconductors. Solutions of electrolytes are good conductors due to the presence of anions and cations. The study of electrolytic solutions has shown that electrolytes may be divided into two classes ionophores and ionogens [134]. lonophores (like alkali halides) are ionic in the crystalline state and they exist only as ions in the fused state as well as in dilute solutions. Ionogens (like hydrogen halides) are substances with molecular crystal lattices which form ions in solution only if a suitable reaction occurs with the solvent. Therefore, according to Eq. (2-13), a clear distinction must be made between the ionization step, which produces ion pairs by heterolysis of a covalent bond in ionogens, and the dissociation process, which produces free ions from associated ions [137, 397, 398]. 

Now, the first requirement of an electrolyte is that it should give rise to a conducting solution. From this point of view, it appears that acetic acid will never answer the requirements of an electrolyte it is nomomc. When, however, acetic add is dissolved in water, an interesting phenomenon oeeurs ions are produced, and therefore the solutions conduct electricity. Thus, acetic acid, too, is a type of eleetrolyte it is not a true electrolyte, but a potential one ( one which can, but has not yet, become ). Potential electrolytes are also called ionogens, i.e., ion producers. ... 

The result of the proton transfer is that two ions have been produced (1) an acetate ion and (2) a hydrated proton. Thus, potential electrolytes (organic acids and most bases) dissociate into ions by ionogenic, or ion-forming, chemical reactions with solvent molecules, in contrast to true electrolytes, which often give rise to ionic solutions by physical interactions between ions present in the ionic crystal and solvent molecules (Fig. 3.1). 

As the main part of this section deals with anticorrosive pigments as such, we shall not go into more detail on the discussion of corrosion processes in this section. However, it should be mentioned that one key feature of the electrochemical process of corrosion is the presence of an electrolyte. This electrolyte is made up of rain, snow and dew, leading to ionogenic surface contamination. The electrolyte contains material coming from airborne pollution, such as dirt, water-soluble chloride and sulfate salts. Chlorides and sulfates are well known as so-called corrosion stimulators, which have a distinct influence on the course of the corrosion reactions [5.51, 5.54]. 

Strictly speaking, the term electrolyte should refer to the conducting system as a whole, but it is also frequently applied to the solute the word ionogen, i.e., producer of ions, has been suggested for the latter [see, for example, Blum, Trons. Eledrochem. Soc., 47, 125 (1925)], but this has not come into general use. 

It is possible to obtain more reliable quantitative information on the conformational and structural characteristics of polymer chains by studying EB in solutions of polypeptides that do not contain ionogenic groups and using non-electrolytic spiralizing systems as solvents ° ... 

The picture is different for weak electrolytes which include most organic acids. A. Hantzsch has demonstrated spectroscopically that an organic acid in water exists in two forms. One has the same structure as the ester of the acid (undissociated form), while the other has the salt structure (ionogenic form). The latter probably dissociates completely into ions, as do strong electrolytes, and it is really unnecessary even to speak of an ionogenic form. 

It is important to note that ionophores are not always completely dissociated. For example, when NaCl is dissolved in a solvent of lower relative permittivity, such as methanol, it is ion paired to some extent. The thermodynamics of systems with ion pairing is considered separately in section 3.10. Under these circumstances the ionophore behaves in the same way as a weak electrolyte. On the other hand, all ionogenes are not weak electrolytes. For example, HCl, which is a molecule in the gas phase, is completely dissociated in water and therefore is a strong electrolyte. Acetic acid is completely dissociated in liquid ammonia, which is a much stronger base than water. Thus, the solvent plays an important role in determining the extent of electrolyte dissociation in solution. In the following discussion the traditional terms, strong and weak electrolytes, are used. 

Churaev, Nikologorodskaya, and co-workers (33) investigated the Brownian and electrophoretic motion of silica hydrosol particles in aqueous solutions of an electrolyte at different concentrations of poly(ethylene oxide) (PEO) in the disperse medium. The adsorption isotherms of PEO on the surface of silica particles were obtained. The thickness of the adsorption layers of PEO was determined as a function of the electrolyte concentration and the pH of the dispersed medium. The results can be used in an analysis of the flocculation and stabilization conditions for colloidal dispersions of silica (with non-ionogenic water-soluble polymers of the PEO type). 

The foregoing method was used to study fluctuations in solutions of strong electrolytes (45) and in ionogenic and nonionogenic micellar colloids (22). Strong electrolytes were chosen to represent 1 1 electrolytes with nearly equal (NaCl) and significantly different (HCl) mobilities of anions and cations and a 2 1 electrolyte (CaCl2). 

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