Electrochemistry

Electrochemistry

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

Answer

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 = Λmo
= 39.05 / 390.5 = 0.1

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