Kohlrausch's Law of Independent Migration of Ions:
Statement:
Kohlrausch's law of independent migration of ions states that the molar conductivity of an electrolyte at infinite dilution is the sum of the contributions of the individual ions present in the electrolyte. In other words, the conductivity of a solution at infinite dilution is determined by the conductivity of each ion in the solution when it is not affected by the presence of other ions.
Mathematical Form:
The molar conductivity (\(\Lambda_m^\infty\)) at infinite dilution for a strong electrolyte can be expressed as:
\(\Lambda_m^\infty = \lambda_+^\infty + \lambda_-^\infty\)
where: - \(\Lambda_m^\infty\) is the molar conductivity at infinite dilution of the electrolyte. - \(\lambda_+^\infty\) is the limiting molar conductivity of the cation. - \(\lambda_-^\infty\) is the limiting molar conductivity of the anion.
Implication:
According to this law, the contributions of the cation and anion to the total conductivity are independent of each other. This is particularly useful in calculating the conductivity of electrolytes at infinite dilution and in understanding the behavior of ions in a solution.
The molar conductance of an infinitely dilute solution of ammonium chloride was found to be 185 S cm$^{-1}$ mol$^{-1}$ and the ionic conductance of hydroxyl and chloride ions are 170 and 70 S cm$^{-1}$ mol$^{-1}$, respectively. If molar conductance of 0.02 M solution of ammonium hydroxide is 85.5 S cm$^{-1}$ mol$^{-1}$, its degree of dissociation is given by x $\times$ 10$^{-1}$. The value of x is ______. (Nearest integer)
Consider the following half cell reaction $ \text{Cr}_2\text{O}_7^{2-} (\text{aq}) + 6\text{e}^- + 14\text{H}^+ (\text{aq}) \longrightarrow 2\text{Cr}^{3+} (\text{aq}) + 7\text{H}_2\text{O}(1) $
The reaction was conducted with the ratio of $\frac{[\text{Cr}^{3+}]^2}{[\text{Cr}_2\text{O}_7^{2-}]} = 10^{-6}$
The pH value at which the EMF of the half cell will become zero is ____ (nearest integer value)
[Given : standard half cell reduction potential $\text{E}^\circ_{\text{Cr}_2\text{O}_7^{2-}, \text{H}^+/\text{Cr}^{3+}} = 1.33\text{V}, \quad \frac{2.303\text{RT}}{\text{F}} = 0.059\text{V}$
| Concentration of KCl solution (mol/L) | Conductivity at 298.15 K (S cm-1) | Molar Conductivity at 298.15 K (S cm2 mol-1) |
|---|---|---|
| 1.000 | 0.1113 | 111.3 |
| 0.100 | 0.0129 | 129.0 |
| 0.010 | 0.00141 | 141.0 |