Self-ionization process

The studies of Bunton et al (Ref 38) using heavy oxygen (18Q) are particularly noteworthy in elucidating the self-ionization process. With moderately dilute nitric acid they found that nitrations required presence of nitrous acid. Ingold and co-workers (Ref 36c) suggest that the action of nitrous acid is as follows ... 

There is evidence that Lewis acids initiate a slow polymerization in some (but not most) systems by a self-ionization process in addition to the coinitiation process [Balogh et al., 1994 Grattan and Plesch, 1980 Masure et al., 1978, 1980], Two mechanisms are possible for self-initiation. One involves bimolecular ionization... 

The classical Self-Stahilization and Self-Ionization Processes 56... 

The Classical Self-Stabilization and Self-Ionization Processes... 

One notable exception to the solvents we shall study is liquid SO2. The solvent-based definition of acids and bases described above was first put forward for SO2, for which the self-ionization process 8.14 was proposed. 

Pure sulfuric acid undergoes self-ionization processes. The most important is ... 

However, a competing equilibrium is established which arises from the self-ionization process of H2SO4 described in part (a) ... 

Water, hydroxyl, and hydrogen ions have very special electrical properties. Water is strongly polar, but it is also to a small extent an electrolyte in itself. From Table 2.2, we see that the intrinsic conductivity is low, but it is not zero. The small rest conductivity is due to a protonic self-ionizing process. There is a small statistical chance that a water molecule transfers one of its protons to another water molecule in the following way ... 

Equation (11.7) has an equilibrium constant (often represented as K ) of approximately 1.0 X 10 (at 298 K), and a simple acid-base equilibrium calculation yields the result that, in pure water, [H30 ] = [OH ] = 1.0 X lO M. It follows that the pH (-log[H30+] = -log[H ]) ofwater is 7.00 at room temperature. Equation (11.7), then, is the basis of the pH scale as commonly presented in general chemistry. Any substance that raises the concentration of H30 ions produces a pH less than 7 and is an acid. Any substance that lowers the concentration of the hydronium ion or raises the concentration of the hydroxide ion produces a pH greater than 7 and is a base. Note that the small value of indicates that the self-ionization process occurs only to a very small extent. Another way to appreciate just how few hydronium ions there are in pure water is to realize that the concentration of water molecules in pure water is 55.6 M therefore, for every hydronium ion, there are (55.6/1.0 X 10 =) 556 X 10, or 556 million water molecules. 

To illustrate the above discussion, let us consider phosphoros oxochloride, POClj as an example of ionizing solvents. The self-ionization process of liquid POClj may be described by the following equation ... 

It should be emphasized that the classic solvosystem concept considers the self-ionization process to be primary, whereas the resultant substances such as acids and bases are obtained on the basis of their reaction with solvent or its constituent components. However, the practice of investigation of acid-base equihbria in solutions consists of studies of donor-acceptor reactions with transfer of a definite component (acid or base) in different solvents irrespective of the fact whether it is able to dissociate with the formation of a... 

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