WHAT IS THE THEORY OF ELECTROLYTIC DISSOCIATION? - SCIENCE - 2025

The theory of electrolytic dissociation refers to the separation of an electrolyte molecule into its constituent atoms. Electron dissociation is the separation of a compound into its ions in the incoming solution. Electrolytic dissociation occurs as a result of the interaction of the solute and the solvent.

Results performed on spectroscopes indicate that this interaction is primarily chemical in nature. In addition to the solvation capacity of solvent molecules and the dielectric constant of the solvent, a macroscopic property, it also plays an important role in electrolytic dissociation.

The classical theory of electrolytic dissociation was developed by S. Arrhenius and W. Ostwald during the 1880s. It is based on the assumption of incomplete dissociation of the solute, characterized by the degree of dissociation, which is the fraction of the molecules in the electrolyte that dissociate.

The dynamic equilibrium between dissociated molecules and ions is described by the law of mass action.

There are several experimental observations that support this theory, including: the ions present in solid electrolytes, the application of Ohm's Law, the ionic reaction, the heat of neutralization, the abnormal colligative properties, and the color of the solution, among others.

Electrolytic dissociation theory

This theory describes aqueous solutions in terms of acids, which dissociate to offer hydrogen ions, and bases, which dissociate to offer hydroxyl ions. The product of an acid and a base is salt and water.

This theory was exposed in 1884 to explain the properties of electrolyte solutions. It is also known as ion theory.

Main bases of the theory

When an electrolyte is dissolved in water, it separates into two types of charged particles: one charging a positive charge and the other with a negative charge. These charged particles are called ions. The positively charged ions are called cations and those that are negatively charged are referred to as anions.

In its modern form, the theory assumes that solid electrolytes are composed of ions that are held together by the electrostatic forces of attraction.

When an electrolyte is dissolved in a solvent, these forces are weakened and then the electrolyte goes through a dissociation into ions; the ions are dissolved.

The process of separating the molecules into ions in an electrolyte is called ionization. The fraction of the total number of molecules present in solution as ions is known as the degree of ionization or degree of dissociation. This degree can be represented by the symbol α.

It has been observed that all electrolytes do not ionize to the same level. Some are almost completely ionized, while others are weakly ionized. The degree of ionization depends on several factors.

The ions present in the solution constantly come together to form neutral molecules, thus creating a state of dynamic equilibrium between ionized and non-ionized molecules.

When an electrical current is transmitted through the electrolyte solution, the positive ions (cations) move toward the cathode, and the negative ions (anions) move toward the anode to discharge. This means that electrolysis occurs.

Electrolyte solutions

Electrolytic solutions are always neutral by nature since the total charge of one set of ions is always equal to the total charge of the other set of ions. However, it is not necessary that the number of the two sets of ions must always be equal.

The properties of the electrolytes in the solution are the properties of the ions present in the solution.

For example, an acidic solution always contains H + ions while the basic solution contains OH- ions and the characteristic properties of solutions are those with H- and OH- ions respectively.

The ions act as molecules toward the freezing point depression, raising the boiling point, lowering the vapor pressure, and establishing the osmotic pressure.

The conductivity of the electrolytic solution depends on the nature and the number of ions when the current is charged through the solution by the movement of ions.

Ions

The classical theory of electrolytic dissociation is applicable only to dilute solutions of weak electrolytes.

Strong electrolytes in dilute solutions are virtually completely dissociated; consequently the idea of ​​an equilibrium between ions and dissociated molecules is not important.

According to chemical concepts, the most complex ion pairs and aggregates are formed in solutions of strong electrolytes in medium and high concentrations.

Modern data indicate that ion pairs consist of two oppositely charged ions in contact or separated by one or more solvent molecules. The ion pairs are electrically neutral and do not participate in the transmission of electricity.

In relatively dilute solutions of strong electrolytes, the equilibrium between individually dissolved ions and ion pairs can be described roughly in a manner similar to the classical theory of electrolytic dissociation by constant dissociation.

Factors related to the degree of ionization

The degree of ionization of an electrolyte solution depends on the following factors:

• Nature of the solute: When the ionizable parts of a substance's molecule are held together by covalent bonds rather than electrovalent bonds, fewer ions are supplied into the solution. These substances are certain weak electrolytes. For their part, strong electrolytes are almost completely ionized in solution.
• Nature of the solvent: the main function of the solvent is to weaken the electrostatic forces of attraction between two ions to separate them. Water is considered the best solvent.
• Dilution: the ionization capacity of an electrolyte is inversely proportional to the concentration of its solution. Therefore, the degree of ionization increases with increasing dilution of the solution.
• Temperature: the degree of ionization increases with increasing temperature. This is because at higher temperatures, the molecular speed increases, exceeding the attractive forces between the ions.

References

1. Electrolytic dissociation. Retrieved from dictionary.com.
2. Electrolytic dissociation. Recovered from encyclopedia2.thefreedictionary.com.
3. Theory of Electrolytic dissociation. Recovered from vocabulary.com.
4. Arrhenius theory of clectrolytic dissociation. Recovered from asktiitians.com.