Question

The molar conductance of NaCl, HCl and CH₃COONa at infinite dilution are 126.45, 426.16 and 91.0 S cm² mol⁻¹ respectively. The molar conductance of CH₃COOH at infinite dilution is ______.

Choose the right option for your answer.

Options

• 540.48 S cm² mol⁻¹

• 201.28 S cm² mol⁻¹

• 390.71 S cm² mol⁻¹

• 698.28 S cm² mol⁻¹

Answer 1

The molar conductance of NaCl, HCl and CH₃COONa at infinite dilution are 126.45, 426.16 and 91.0 S cm² mol⁻¹ respectively. The molar conductance of CH₃COOH at infinite dilution is 390.71 S cm² mol⁻¹.

Explanation:

Use Kohlrausch’s Law of Independent Ionic Migration:

\[\ce{\Lambda^{\circ}_m​(CH3COOH) = \Lambda^{\circ}_m​(HCl) + \Lambda^{\circ}_m​(CH3COONa) − \Lambda^{\circ}_m​(NaCl)}\]

Substitute the values:

= 426.16 + 91.00 − 126.45

= 390.71 S cm² mol⁻¹

Therefore, the molar conductance of acetic acid at infinite dilution is 390.71 S cm² mol⁻¹.