Give the applications of Kohlracsch's law of independent migration of ions.

Explanation

Kohlrasuch's law of independent migration of ions: The limigting molar conductivity of an electrolytes can be represented as the sum of the indibvidual contributions of the anion and the cation of the electrolyes.
`lamda _(m(AB))^(0) =lamda_(A)^(0)+lamda_(B)^(0)`
`lamda_(m)^(0) =` Limiting molar conductivity
`lamda _(A^(+))^(0)=` Limiting molar conductivity of cation
`lamda_(B^(-))^(0)=` Limiting molar conductivity of anion
Applicatiions :
1) Calculation of limiting molar conductance at infinite dilution `(^^_(oo))` of weak electrolytes:
Limiting molar conductance of weak electrolytes at infinite dilution cannot be obtained graphically by extropolation method. However the application of Kohlrausch's law enables indirect evaluastions in such cases.
Eg: Limiting molar conductance of acetic acid at infinite dilution can be calculated from the limiting molar conductances at infinite dilution of hydrochloride acid, sodium chloride and sodium acetate, as illustrated below :
`^^_(oo)of CH_(3)COO" "=^^_(oo) CH_(3) COONa+^^_(oo)^(HCl) -^^_(oo)^(NaCl`
`=lamda_(alpha)CH_(3)COcancelO^(-)+ cancel (lamda_(alpha)^(Na^(+)))+cancel(lamda _(a)^(H^(+)))+cancel (lamda_(a))^(H^(+))+cancel(lamda_(alpha)^(Na^(+)))-lamda_(a)^(Cl^(-))`
`=lamda_(a)CH_(3)COO^(-)+lamda_(alpha)^(H^(+))`
2) Calculation of degree of dissocistion of a weak electrolyte :
Degree of dissociation `(alpha) =(lamda_(v))/(lamda_(oo))`
where `lamda _(v)=` Limiting molar conductivity of given electrolyte at infinite dilution.
3) Calculation of the solubility (s) of sparingly soluble salts like `AgCl, BaSO_(4)` etc.
`S=(k xx 1000)/(^^_(oo))`
where k = specific conductance
`^^_(oo)=` Limiting molar conductance at infinite dilution.