Electrolyte solutions are special liquids that are partially or completely in the form of charged particles (ions). The process of splitting molecules into negative (anions) and positively charged (cations) particles is called electrolytic dissociation. Dissociation in solutions is possible only due to the ability of ions to interact with the molecules of the polar liquid, which acts as a solvent.
What are electrolytes
Electrolyte solutions are divided into aqueous and non-aqueous. Water has been studied quite well and is very widespread. They are present in almost every living organism and are actively involved in many important biological processes. Non-aqueous electrolytes will be used for conducting electrochemical processes and various chemical reactions. Their use led to the invention of new chemical energy sources. They play an important role in photoelectrochemical cells, organic synthesis, electrolyte capacitors.
Electrolyte solutions, depending on the degree of dissociation, can be divided into strong, medium and weak. The degree of dissociation (Ξ±) is the ratio of the number of molecules disintegrated into charged particles to the total number of molecules. For strong electrolytes, the value of Ξ± approaches 1, for medium electrolytes Ξ±β0.3, and for weak ones Ξ± <0.1.
Strong electrolytes usually include salts, a number of some acids - HCl, HBr, HI, HNO 3 , H 2 SO 4 , HClO 4 , hydroxides of barium, strontium, calcium and alkali metals. Other bases and acids are electrolytes of medium or weak strength.
Properties of electrolyte solutions
The formation of solutions is often accompanied by thermal effects and volume changes. The process of dissolution of the electrolyte in a liquid takes place in three stages:
- The destruction of the intermolecular and chemical bonds of the dissolved electrolyte requires the expenditure of a certain amount of energy, and therefore, heat is absorbed (β bit > 0).
- At this stage, the solvent begins to interact with electrolyte ions, resulting in the formation of solvates (hydrates in aqueous solutions). This process is called solvation and is exothermic, i.e. heat is generated (β H hydr <0).
- The last stage is diffusion. This is a uniform distribution of hydrates (solvates) in the volume of the solution. This process requires energy costs and, therefore, the solution is cooled (Ξ differential > 0).
Thus, the total thermal effect of dissolution of the electrolyte can be written in the following form:
Ξ sol = Ξ bit + Ξ hydr + Ξ differential
The final sign of the general thermal effect of electrolyte dissolution depends on what the constituent energy effects turn out to be. Usually this process is endothermic.
The properties of a solution depend primarily on the nature of its constituent components. In addition, the composition of the solution, pressure and temperature influence the properties of the electrolyte.
Depending on the solute content, all electrolyte solutions can be divided into extremely diluted (which contain only βtracesβ of electrolyte), diluted (with a small content of solute) and concentrated (with a significant electrolyte content).
Chemical reactions in electrolyte solutions that are caused by the passage of electric current lead to the release of certain substances on the electrodes. This phenomenon is called electrolysis and is often used in modern industry. In particular, aluminum, hydrogen, chlorine, sodium hydroxide, hydrogen peroxide and many other important substances are obtained through electrolysis.