Question

The molar conductance of acetic acid at infinite dilution is ${\lambda }_{\infty }$. If the specific conductivity of 0.1M acetic acid is S, the apparent degree of ionisation is:

• A. $\frac{10000S}{{\lambda }_{\infty }}$
• B. $\frac{10S}{{\lambda }_{\infty }}$
• C. $\frac{{\lambda }_{\infty }}{100S}$
• D. $\frac{100000}{{\lambda }_{\infty }S}$

Answer 1

The correct option is A $\frac{10000S}{{\lambda }_{\infty }}$

The degree of the dissociation is equal to the ratio of the molar conduction at dilution to the molar conduction at infinite dilution. $\alpha =\frac{{\lambda }_m}{{\lambda }_{\infty }}$.

The relationship between the molar conductivity and the specific conductance is ${\lambda }_m=\frac{\kappa \times 1000}{M}$ .

Substitute $\kappa =S$ and $M=0.1M$ in the above equation.

$\alpha =\frac{\frac{1000\times S}{0.1}}{{\lambda }_{\infty }}=\frac{10000S}{{\lambda }_{\infty }}$

Option A is correct.