Theory of Strong Electrolytes

The interionic forces of the strong electrolytes depend on the solvent's dielectric constant, which is the ability of a solvent to store electrical energy, based on its polarizability. and the solution's concentration. In high-dielectric solvents and in dilute solutions, weak electrostatic forces keep ions apart. However, in low-dielectric solvents or concentrated solutions, stronger interionic forces may cause ions to pair up as ionic doublets despite being fully ionized. The theory of strong electrolytes also suggests that strong electrolytes maintain a degree of ionization of unity even at substantial concentrations. Debye and Hückel introduced the concept that the increase in molar conductance with dilution for strong electrolytes is a result of heightened ion mobilities because of reduced interionic attractions, not increased ionization. This theory posits that in strong electrolytes, the interionic attraction, rather than partial dissociation, accounts for the decrease in conductivity with increasing concentration. Debye and Huckel's equation measures the impact of interionic effects, proposing that each ion is surrounded by an 'ionic atmosphere' of opposite charge. This atmosphere is shaped by the coulombic interactions and thermal collisions between ions and solvent molecules. At high temperatures, this structure becomes less organized due to increased thermal collisions. When an electric field is applied, the ions move, disrupting the ionic atmosphere's symmetry and slowing down the ion movement, known as the 'asymmetry effect.' At higher concentrations, ion movement can be slowed down due to the electrophoretic and viscous effects. The electrophoretic effect occurs when the ionic atmosphere associated with water molecules moves in the opposite direction to the central ion, creating counter-currents that impede ion movement. The viscous effect results from the solvent's viscous drag on the ions' movement. The more viscous the solvent, the stronger the drag, resulting in decreased ionic mobility and conductance.