Question

A graph of molar conductivity of three electrolytes (NaCl, HCl and NH4 OH) is plotted against $\sqrt{C}$

$\lambda_m$

$\sqrt{C}$

Answer 1

• Curve 1: HCl
• Curve 2: NaCl
• Curve 3: NH₄OH

Answer 2

For strong electrolytes, Kohlrausch’s law applies:

$$\Lambda_m = \Lambda_m^0 - A\sqrt{C}$$

so their plots vs. $\sqrt{C}$ are straight lines. Among strong electrolytes, HCl has a very high limiting molar conductivity (due to the high mobility of $H^+$) compared to NaCl. Therefore, the electrolyte with the highest y-intercept (Curve 1) is HCl and the one with the lower intercept (Curve 2) is NaCl. A weak electrolyte like $\mathrm{NH_4OH}$ shows a non‐linear behavior (curved plot) as its degree of dissociation increases on dilution, which corresponds to Curve 3.