Question

At $25{}^{\circ }C$molar conductance of $0.1$ $\text{molar}$ aqueous solution of ammonium hydroxide is $9.54{\text{ohm}}^{-1}{\text{cm}}^2{\text{mol}}^{-1}$ undertaken by dilution its molar conductance at infinite is $238{\text{ohm}}^{-1}{\text{cm}}^2{\text{mol}}^{-1}$. The percentage degree of ionization of ammonium hydroxide at the same concentration and temperature is:

• A. $4.008\%$
• B. $2.080\%$
• C. $20.800\%$
• D. $40.800\%$

Answer 1

The correct option is A $4.008\%$

Molar conductance of $0.1\text{M}$ concentration, ${\lambda }_c=9.54{\Omega }^{-1}{\text{cm}}^2{\text{mol}}^{-1}$
Molar conductance at infinite concentration, ${\lambda }_{\infty }=9.54{\Omega }^{-1}{\text{cm}}^2{\text{mol}}^{-1}$
$\%\alpha =\frac{{\lambda }_c}{{\lambda }_{\infty }}=\frac{9.54}{238}\times 100=4.008\%$