Question

The conductivity of \(0.001\ \mathrm{M}\) acetic acid is \(5\times10^{-5}\ \mathrm{S\,cm^{-1}}\). If the molar conductivity of acetic acid solution at infinite dilution is \(390.5\ \mathrm{S\,cm^2\,mol^{-1}}\), what is the degree of dissociation?

• A. 0.218
• B. 0.128
• C. 0.138
• D. 0.238 \bigskip

Hint:

For weak electrolytes, \[ \boxed{\Lambda_m=\frac{1000\kappa}{C}} \] and \[ \boxed{\alpha=\frac{\Lambda_m}{\Lambda_m^\circ}} \]

Answer 1

The Correct Option is B

Concept: Degree of dissociation \(\alpha = \Lambda_m/\Lambda_m^\circ\). \(\Lambda_m = 1000\kappa/C\).

Step 1: \(\Lambda_m = 1000\times5\times10^{-5}/0.001 = 50\) S cm² mol⁻¹. \(\alpha = 50/390.5 = 0.128\).

Step 2: Write the final answer. \(\boxed{\alpha=0.128}\)