What factors dose controlling the degree of ionization ? Ionic Equilibria ? In Physical Chemistry .

 FACTORS CONTROLLING THE DEGREE OF IONIZATION.

The degree of ionization depends on the following factors :

(1) Nature of the electrolyte : Weak electrolytes such as CH₃COOH, H₂CO₃, NH₄OH , Mg(OH)₂ etc. can ionize only to a small extent, therefore, their degree of ionization is low. Strong electrolytes Such as HCI, NaOH, NaCl which are almost completely ionized have high degree of ionization.

(2) Nature of the solvent : Every solvent has some detinite value of dielectric constant. Generally, solvents with high dielectric constant such as water (ε= 80) ionize the electrolytes to greater extent than the solvents with low dielectric constant such as benzene (ε = 2). This is due to the fact that solvents having high dielectric constant weakens the forces of attraction between the oppositely charged ions and hence enhance ionization.

(3) Concentration: lonization of the electrolyte increases with the increase in dilution and it becomes naximum at infinite dilution i.e. as concentration approaches zero.

(4) Temperature: The degree of ionization increases with the increase in temperature. This is due the fact that at higher temperature, molecular speed is increased which overcomes the forces of attraction between the ions.

(5) Presence of common ions : The degree of ionization of an electrolyte decreases in the presence of another electrolyte which furnishes, a common ion. For example, ionization of CH₃COOH decreases in the presence of CH₃COONa due to common ion (CH₃COO⁻) effect.