Electrical Engineering ⇒ Topic : Mechanism of Ionisation

Mechanism of Ionisation

The splitting up of an ionic compound in solution into ions is known as ionisation or ionic dissociation. Let us take the example of sodium chloride (NaC1). The structure of this solid crystalline salt is made up of Na⁺ and C1^- ions. When in solid state, there is a very strong force of attraction between Na⁺ and C1^- ions which holds them together as a molecule of NaCl. However, when sodium chloride is dissolved in water, the force of attraction between the ions (Na⁺ and C1^-) of sodium chloride molecule is tremendously *reduced due to high permittivity of water (K = 81).In fact, the force of attraction between ions reduces 81 times. The result is that sodium ion (Na⁺)and C1^- ion get separated. This process is called ionisation. It may be noted that as soon as sodium chloride is dissolved in water, ions are formed. In other words, ions are present in an electrolytic solution even before it conducts electric current.