Question

What is Kohlrausch law? Write its two applications.

Hint:

Kohlrausch's law is very useful for weak electrolytes like acetic acid. By knowing the \(\Lambda_m^\infty\) values of strong electrolytes, we can indirectly calculate \(\Lambda_m^\infty\) of weak electrolytes.

Answer 1

Statement of Kohlrausch's Law:
At infinite dilution, the molar conductivity of an electrolyte is equal to the sum of the contributions of its individual ions.
\[ \Lambda_m^\infty = \lambda^0_+ + \lambda^0_- \] where \(\lambda^0_+\) and \(\lambda^0_-\) are the limiting molar conductivities of cations and anions respectively.
Applications:
1. To calculate the molar conductivity of weak electrolytes at infinite dilution (since they cannot be measured directly).
2. To determine the degree of dissociation (\(\alpha\)) and dissociation constant (\(K_a, K_b\)) of weak electrolytes.