Almost everyone knows the definition of electric current as the directed movement of charged particles. However, the whole point is that its origin and movement in different media is quite different from each other. In particular, the electric current in liquids has slightly different properties than the ordered motion of charged particles. We are talking about the same metal conductors.
The main difference is that the current in liquids is the movement of charged ions, that is, atoms or even molecules that for some reason have lost or acquired electrons. Moreover, one of the indicators of this movement is a change in the properties of the substance through which these ions pass. Based on the definition of electric current, we can assume that during decomposition, negatively charged ions will move towards a positive current source, and positive ones, on the contrary, to a negative one.
The process of decomposition of solution molecules into positive and negative charged ions is called electrolytic dissociation in science. Thus, an electric current in liquids arises due to the fact that, unlike the same metal conductor, the composition and chemical properties of these liquids change, resulting in the process of movement of charged ions.
The electric current in liquids, its origin, quantitative and qualitative characteristics were one of the main problems that the famous physicist M. Faraday has been studying for a long time. In particular, with the help of numerous experiments, he was able to prove that the mass of the substance released during electrolysis directly depends on the amount of electricity and the time during which this electrolysis was carried out. This mass does not depend on any other reasons, with the exception of the nature of the substance.
In addition, by studying the current in liquids, Faraday experimentally found that the selection of one kilogram of any substance during electrolysis requires the same amount of electric charges. This amount, equal to 9.65 • 10 7 K., was called the Faraday number.
Unlike metal conductors, the electric current in liquids is surrounded by water molecules, which greatly complicate the movement of ions of the substance. In this regard, in any electrolyte, only a small voltage current can be generated. At the same time, if the temperature of the solution rises, then its conductivity increases, and the electric field increases.
Electrolysis has another interesting property. The thing is that the probability of decay of a particular molecule into positive and negative charged ions is the higher, the greater the number of molecules of the substance itself and the solvent. At the same time, at a certain moment, the solution becomes supersaturated with ions, after which the conductivity of the solution begins to decrease. Thus, the strongest electrolytic dissociation will take place in a solution where the concentration of ions is extremely low, however, the electric current in such solutions will be extremely low.
The electrolysis process has been widely used in various industrial industries related to the conduct of electrochemical reactions. Among the most important of these are the production of metal using electrolytes, the electrolysis of salts containing chlorine and its derivatives, redox reactions, the production of such a necessary substance as hydrogen, polishing surfaces, electroplating. For example, at many enterprises of machine and instrument engineering, the refining method, which is the production of metal without any unnecessary impurities, is very common.