Assertion: At infinite dilution, both strong and weak electrolyte have degree of ionization equal to unity.Reason: At infinite dilution of an electrolyte, the equivalent conductance of cations and anions are independent of each other.
The correct option is A Both Assertion and Reason are true and Reason is the correct explanation of Assertion
At infinite dilution, the equivalent conductance of cations and anions are independent of each other. At infinite dilution, weak and strong electrolytes have a degree of dissociation equal to 1.
In general, conductance of an electrolyte depends on the following factors,
(1) Nature of electrolyte: The conductance of an electrolyte depends upon the number of ions present in the solution. Therefore, the greater the number of ions in the solution the greater is the conductance. The number of ions produced by an electrolyte depends upon its nature. The strong electrolytes dissociate almost completely into ions in solutions and, therefore, their solutions have high conductance. On the other hand, weak electrolytes, dissociate to only small extents and give lesser number of ions. Therefore, the solutions of weak electrolytes have low conductance.
(2) Concentration of the solution: The molar conductance of electrolytic solution varies with the concentration of the electrolyte. In general, the molar conductance of an electrolyte increases with decrease in concentration or increase in dilution.
The molar conductance of strong electrolyte (HCl,KCl,KNO3) as well as weak electrolytes (CH3COOH.NH4OH) increase with decrease in concentration or increase in dilution. The variation is however different for strong and weak electrolytes.
The variation of molar conductance with concentration can be explained on the basis of conducting ability of ions for weak and strong electrolytes.
For weak electrolytes, the variation of Λ with dilution can be explained on the bases of number of ions in solution. The number of ions furnished by an electrolyte in solution depends upon the degree of dissociation with dilution. With the increase in dilution, the degree of dissociation increases and as a result, molar conductance increases. The limiting value of molar conductance (Λ0) corresponds to degree of dissociation equal to 1 i.e., the whole of the electrolyte dissociates.
In general, conductance of an electrolyte depends on the following factors,
(1) Nature of electrolyte: The conductance of an electrolyte depends upon the number of ions present in the solution. Therefore, the greater the number of ions in the solution the greater is the conductance. The number of ions produced by an electrolyte depends upon its nature. The strong electrolytes dissociate almost completely into ions in solutions and, therefore, their solutions have high conductance. On the other hand, weak electrolytes, dissociate to only small extents and give lesser number of ions. Therefore, the solutions of weak electrolytes have low conductance.
(2) Concentration of the solution: The molar conductance of electrolytic solution varies with the concentration of the electrolyte. In general, the molar conductance of an electrolyte increases with decrease in concentration or increase in dilution.
The molar conductance of strong electrolyte (HCl,KCl,KNO3) as well as weak electrolytes (CH3COOH.NH4OH) increase with decrease in concentration or increase in dilution. The variation is however different for strong and weak electrolytes.
The variation of molar conductance with concentration can be explained on the basis of conducting ability of ions for weak and strong electrolytes.
For weak electrolytes, the variation of Λ with dilution can be explained on the bases of number of ions in solution. The number of ions furnished by an electrolyte in solution depends upon the degree of dissociation with dilution. With the increase in dilution, the degree of dissociation increases and as a result, molar conductance increases. The limiting value of molar conductance (Λ0) corresponds to degree of dissociation equal to 1 i.e., the whole of the electrolyte dissociates.
