Question

The degree of dissociation of acetic acid in its 0.1 M solution is 0.0132 at 25°C. Calculate the degree of dissociation in its 0.01 M solution.

Answer 1

Given: C = 0.1 M, ∝ = 0.0132, C' = 0.01 M, ∝ = 0.0132, ∝' = ?

K_a = ∝²C

C = Molar concentration of acetic acid = 0.1 M

∝ = Degree of dissociation in 0.1 M solution = 0.0132

`∴ ∝ = sqrt(K_a/C)`

If the concentration is `C^',∝^' = sqrt(K_a/(C^'))`

`∴ ∝^'/∝ = sqrt(C/C^') = sqrt(0.1/0.01) = sqrt10`

`∝^' = ∝sqrt10 = 1.32 xx 10^-2 sqrt10`

= 4.175 × 10⁻²

∴ degree of dissociation in 0.01 M solution = 4.175 × 10⁻²