Question
Calculate the degree of dissociation (a) of acetic acid if its molar conductivity (Λm) is 39.05 S cm2mol–1. Given λo(H+) = 349.6 S cm2 mol–1 and λo(CH3COO–) = 40.9 S cm2 mol–1
Solution
The degree of dissociation is given by,
α = Λm / λo
here, α is the degree of dissociation,
Λm is the molar conductivity
λo is the molar conductivity at infinite dilution.
We have given
λo(H+) = 349.6 S cm2mol-1
and
λ0(CH3COO-) = 40.9 S cm2mol-1
then,
λoCH3COOH = λo CH3COO-+ λoH+
λoCH3COOH = 349.6 + 40.9 = 390.5
Now, degree of dissociation (α),
α = Λm /Λo
= 39.05 / 390.5 = 0.1
