Solutions of electrolytes

Solutions of electrolytes are special liquids, which 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 because of the ability of the ions to interact with molecules of the polar liquid, which acts as a solvent.

What are the electrolytes?

Solutions of electrolytes are divided into water and non-aqueous. Water is well studied and received very widespread. They exist in almost every living organism and actively participate in many important biological processes. Non-aqueous electrolytes are used to conduct electrochemical processes and various chemical reactions. Their use led to the invention of new chemical energy sources. They play an important role in photoelectrochemical elements, organic synthesis, electrolyte capacitors.

Solutions of electrolytes, depending on the degree of dissociation, can be divided into strong, medium and weak. The degree of dissociation (α) is the ratio of the number of molecules that have decayed into charged particles to the total number of molecules. In strong electrolytes, the value of α approaches 1, for medium α≈0.3, and for weak α <0.1.

Strong electrolytes usually include salts, a number of certain acids - HCl, HBr, HI, HNO ₃ , H ₂ SO ₄ , HClO ₄ , barium hydroxides, strontium, calcium and alkali metals. Other bases and acids are medium or weak electrolytes.

Properties of solutions of electrolytes

The formation of solutions is often accompanied by thermal effects and a change in volume. The process of dissolving the electrolyte in a 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 (ΔH _times > 0).
2. At this stage, the solvent begins to interact with the electrolyte ions, resulting in the formation of solvates (in aqueous solutions - hydrates). This process is called solvation and is exothermic, i. E. There is a heat release (ΔH _hydr <0).
3. 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 (ΔH _diff > 0).

Thus, the total thermal effect of dissolving the electrolyte can be written in this form:

ΔH _values = ΔH _times + ΔH _hydr + ΔH _diff

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

The properties of the solution depend primarily on the nature of the constituent components. In addition, the properties of the electrolyte affect the composition of the solution, pressure and temperature.

Depending on the solute content, all solutions of electrolytes can be divided into extremely dilute (containing only "traces" of electrolyte), diluted (with a small content of solute) and concentrated (with a significant content of electrolyte).

Chemical reactions in solutions of electrolytes, which are caused by the passage of an 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, thanks to electrolysis, aluminum, hydrogen, chlorine, sodium hydroxide, hydrogen peroxide and many other important substances are obtained.