Question

${\Lambda }_m^{\circ }$ for $NaCl,HCl$ and $NaAc$ are $126.4,425.9$ and $91.0Sc{m}^{2}mo{l}^{-1}$ respectively. ${\Lambda }^{\circ }$ for $HAc$ is

• A. $285Sc{m}^{-2}mo{l}^{-1}$
• B. $400Sc{m}^{2}mo{l}^{-1}$
• C. $390.5Sc{m}^{2}mo{l}^{-1}$
• D. $125Sc{m}^{2}mo{l}^{-1}$

Answer 1

Answer: (C)

${\Lambda }_{m(HAc)}^{\circ }={\lambda }_{H^{+}}^{\circ }+{\lambda }_{A{c}^{-}}^{\circ }$
$={\lambda }_{H^{+}}^{\circ }+{\lambda }_{C{l}^{-}}^{\circ }+{\lambda }_{A{c}^{-}}^{\circ }+{\lambda }_{N{a}^{+}}^{\circ }-{\lambda }_{C{l}^{-}}^{\circ }-{\lambda }_{N{a}^{+}}^{\circ }$
$={\Lambda }_{m(HCl)}^{\circ }+{\Lambda }_{m(NaAc)}^{\circ }-{\Lambda }_{m(NaCl)}^{\circ }$
$=(425.9+91.0-126.4)Sc{m}^{2}mo{l}^{-1}$
$=390.5Sc{m}^{2}mo{l}^{-1}$