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Explain kohlrausch Law with example.

Vidyadip · Accepted Answer

→ "The law states that limiting molar conductivity of an electrolyte can be represented as the sum of the individual contributions of the anion and cation of the electrolyte."
→ Thus, if $\lambda_{ Na ^{+}}^0$ and $\lambda_{ Cl ^{-}}^0$ are limiting molar conductivity of the sodium and chloride ions respectively. then the limiting molar conductivity for sodium chloride is given by the equation :
$
\wedge_{ m ( NaCl )}^0=\lambda_{ Na ^{+}}^0+\lambda_{ Cl ^{-}}^0
$
→ In general, if an electrolyte on dissociation gives $v_{+}$cations and $v_{-}$anions then its limiting molar conductivity is given by :
$
E _{ m }^0= v _{+} \lambda_{+}^0+ v _{-} \lambda^0
$
→ Here, $\lambda_{+}^0$ and $\lambda_{-}^0$ are the limiting molar conductivities of the cation and anion respectively.
$
\begin{array}{l}
→ \text { If } \lambda_{ m ^{+}}^0 \text { for } Na ^{+}=50.1 \ S\ cm ^2\ mol^{-1} \\
\lambda_{ m ^{-}}^0 \text { for } Cl ^{-}=76.3 \ S \ cm ^2 \ mol^{-1} \\
\lambda_{ m ( NaCl )}=\lambda_{ m \left( Na ^{+}\right)}^0+\lambda_{ m \left( Cl ^{-}\right)}^0 \\
=50.1+76.3 \\
=126.4 \ S \ \cdot cm ^2 \ mol^{-1} \\
\end{array}
$

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