Question

The molar conductance of ${}^{NaCl,HCl}\text{and}{}^{C{H}_{3}COONa}$ at infinite dilution are ${}^{126.45,426.16}\text{and}{}^{91.0Sc{m}^{2}mo{l}^{-1}}$ respectively. The molar conductance of ${}^{C{H}_{3}COOH}$ at infinite dilution is. Choose the right option for your answer.

• A. $540.48c{m}^{2}mo{l}^{-1}$
• B. $201.28Sc{m}^{2}mo{l}^{-1}$
• C. $698.28Sc{m}^{2}mo{l}^{-1}$
• D. $390.71Sc{m}^{2}mo{l}^{-1}$

Answer 1

The correct option is D $390.71Sc{m}^{2}mo{l}^{-1}$

Kohlrausch law of independent migration of ions:
${\Lambda }_m^0={\lambda }_{+}^0+{\lambda }_{-}^0$

${\lambda }_{+}^0\to \text{Limiting molar conductivities of cation}$
${\lambda }_{-}^0\to \text{Limiting molar conductivities of anion}$

${\Lambda }_m^{\infty }\left(C{H}_{3}COOH\right)={\Lambda }_m^{\infty }\left(C{H}_{3}COONa\right)+{\Lambda }_m^{\infty }\left(HCl\right)-{\Lambda }_m^{\infty }\left(NaCl\right)$
$=91+426.16-126.45$
$=390.71Sc{m}^{2}mo{l}^{-1}$