Question

If the molar conductivity ($\Lambda_m$) of a 0.050 mol $L^{–1}$ solution of a monobasic weak acid is 90 S $cm^{2} mol^{–1}$, its extent (degree) of dissociation will be:
[Assume: $\Lambda^0$ = 349.6 S $cm^{2} mol^{–1}$ and $\Lambda^0_{\text{acid}}$ = 50.4 S$ cm^{2} mol^{–1}$]

• A. 0.125
• B. 0.225
• C. 0.215
• D. 0.115

Hint:

For weak electrolytes, use \(\alpha = \frac{\Lambda_m}{\Lambda^0_m}\) to find the degree of dissociation from molar conductivities.