Electrolyte solutions

2024 Author: Angel Austin | [email protected]. Last modified: 2023-12-17 05:14

Electrolyte solutions are special liquids that are partially or completely in the form of charged particles (ions). The very process of splitting molecules into negatively (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 ones have been studied quite well and are very widespread. They are found in almost every living organism and are actively involved in many important biological processes. Non-aqueous electrolytes are used to carry out electrochemical processes and various chemical reactions. Their use has led to the invention of new chemical energy sources. They play an important role in photoelectrochemical cells, organic synthesis, electrolytic capacitors.

Electrolyte solutions depending on the degree of dissociation can be divided intostrong, medium and weak. The degree of dissociation (α) is the ratio of the number of molecules decomposed into charged particles to the total number of molecules. For strong electrolytes, the value of α approaches 1, for medium electrolytes α≈0.3, and for weak electrolytes α<0, 1.

Strong electrolytes usually include s alts, a number of some acids - HCl, HBr, HI, HNO₃, H₂SO 4_{, HClO}4_{, hydroxides of barium, strontium, calcium and alkali metals. Other bases and acids are medium or weak electrolytes.}

Properties of electrolyte solutions

The formation of solutions is often accompanied by thermal effects and volume changes. The process of dissolving the electrolyte in the liquid takes place in three stages:

1. The destruction of intermolecular and chemical bonds of the dissolved electrolyte requires the expenditure of a certain amount of energy and therefore heat is absorbed (∆Н_resolved > 0).
2. At this stage, the solvent begins to interact with electrolyte ions, resulting in the formation of solvates (in aqueous solutions - hydrates). This process is called solvation and is exothermic, i.e. heat is released (∆ Н_hydr < 0).
3. The last step 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 (∆Н_dif > 0).

Thus, the total thermal effect of electrolyte dissolution can be written as follows:

∆Н_solv=∆Н_release + ∆Н_hydr + ∆Н _diff

The final sign of the total thermal effect of electrolyte dissolution depends on what the constituent energy effects turn out to be. This process is usually endothermic.

The properties of a solution depend primarily on the nature of its constituent components. In addition, the properties of the electrolyte are affected by the composition of the solution, pressure and temperature.

Depending on the content of the dissolved substance, all electrolyte solutions can be divided into extremely dilute (which contain only "traces" of the electrolyte), dilute (with a small content of the dissolved substance) and concentrated (with a significant content of the electrolyte).

Chemical reactions in electrolyte solutions, which 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, electrolysis produces aluminum, hydrogen, chlorine, sodium hydroxide, hydrogen peroxide and many other important substances.