If the molar conductivity (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 d…

Question

If the molar conductivity (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 λ^+=349.6 S cm^2 mol^-1 and λ^-=50.4 S cm^2 mol^-1]:

1. A. 0.115
2. B. 0.125
3. C. 0.225 (Correct answer)
4. D. 0.215

Correct Answer

Option C — 0.225

Detailed Solution & Explanation

The correct answer is 0.225.

Key Points

• Degree of dissociation $\alpha=\dfrac{\Lambda_m}{\Lambda_m^\circ}$.
• $\Lambda_m^\circ=\Lambda^\circ_++\Lambda^\circ_-=349.6+50.4=400$ S cm$^2$ mol$^{-1}$.
• $\alpha=\dfrac{90}{400}=0.225$.