Which of the following option will be the limiting molar conductivity of `CH_(3)COOH` if the limiting molar conductivity of `CH_(3)COONa` is `91 Scm^(2)mol^(-1)`? Limiting molar conductivity for individual ions are given in the following table.

Options

A. 350 `Scm^(2)mol^(-1)`
B. 375.3 `Scm^(2)mol^(-1)`
C. `390.5Scm^(2)mol^(-1)`
D. `340.4Scm^(2)Scm^(2)mol^(-1)`

Answer

C

Explanation

The limiting molar conductivity `(wedge_(m)^(o))` for strong and weak electrolyte can be determined by using Kohlrausch.s law which states that "the limiting molar conductivity of an electrolyte can be represented as the sum of the indivudual contributions of the anion and cation of the electrolyte."
`wedgeCH_(3)COONa=wedgeCH_(3)COO^(-)+wedgeNa^(+)`
`91Scm^(2)mol^(-1)=wedgeCH_(3)COO^(-)+0.1Scm^(2)mol^(-1)`
`implies wedge CH_(3)COO^(-)=40.9Scm^(2)mol^(-1)`
For acetic acid
`wedgeCH_(3)COOH=wedgeCH_(3)COO^(-)+wedgeH^(+)`
`=40.9Scm^(2)mol^(-1)+349.6Scm^(2)mol^(-1)`
`=390.5Scm^(2)mol^(-1)`