Electrical dissociation plays a huge role in our lives, although we usually don’t think about it. It is with this phenomenon that the electrical conductivity of salts, acids and bases in a liquid medium is associated. From the first heart rhythms caused by “living” electricity in the human body, which is eighty percent composed of liquids, to automobiles, mobile phones and players, the batteries of which are inherently electrochemical batteries, there is invisible electrical dissociation everywhere with us.
In giant tanks emitting toxic fumes from bauxite melted at high temperatures, a winged metal is obtained by the electrolysis method. All objects around us, from chrome radiator grills to silver-plated earrings in our ears, have ever encountered solutions or molten salts, and therefore this phenomenon. No wonder electrical dissociation is studied by a whole branch of science - electrochemistry.
Upon dissolution, the molecules of the solvent liquid enter into chemical bonds with the molecules of the solute, forming solvates. In an aqueous solution of dissociation, salts, acids and bases are most susceptible. As a result of this process, solute molecules can decay into ions. For example, under the influence of an aqueous solvent, the Na + and CI - ions located in the NaCI ion crystal pass into the solvent medium in a new quality of solvated (hydrated) particles.
This phenomenon, which is inherently a process of complete or partial decomposition of a dissolved substance into ions as a result of exposure to a solvent, is called "electrical dissociation". This process is extremely important for electrochemistry. Of great importance is the fact that the dissociation of complex multicomponent systems is characterized by stepwise flow. With this phenomenon, there is also a sharp increase in the number of ions in solution, which distinguishes electrolytic substances from non-electrolytic ones.
In the process of electrolysis, ions have a clear direction of motion: particles with a positive charge (cations) - to a negatively charged electrode, called the cathode, and positive ions (anions) - to the anode, an electrode with an opposite charge, where they are discharged. Cations are reduced and anions are oxidized. Therefore, dissociation is a reversible process.
One of the fundamental characteristics of this electrochemical process is the degree of electrolytic dissociation, which is expressed as the ratio of the number of hydrated particles to the total number of molecules of the dissolved substance. The higher this indicator, the more powerful the electrolyte is this substance. On this basis, all substances are divided into weak, medium strength and strong electrolytes.
The degree of dissociation depends on the following factors: a) the nature of the dissolved substance; b) the nature of the solvent, its dielectric constant and polarity; c) the concentration of the solution (the lower this indicator, the greater the degree of dissociation); g) the temperature of the solvent medium. For example, the dissociation of acetic acid can be expressed by the following formula:
CH 3 COOH H + + CH 3 COO -
Strong electrolytes dissociate almost irreversibly, since in their aqueous solution there are no starting molecules and unhydrated ions. It should also be added that all substances having an ionic and covalent polar type of chemical bonds are subject to the process of dissociation. The theory of electrolytic dissociation was formulated by the prominent Swedish physicist and chemist Svante Arrhenius in 1887.