Question

The equivalent conductance of `"M"/36` solution of a weak monobasic acid is 6 mho cm² equivalent⁻¹ and at infinite dilution is 400 mho cm² equivalent⁻¹. The dissociation constant of this acid is ____________.

Options

• 1.25 × 10⁻⁶

• 6.25 × 10⁻⁶

• 1.25 × 10⁻⁴

• 6.25 × 10⁻⁵

Answer 1

The equivalent conductance of `"M"/36` solution of a weak monobasic acid is 6 mho cm² equivalent⁻¹ and at infinite dilution is 400 mho cm² equivalent⁻¹. The dissociation constant of this acid is 6.25 × 10⁻⁶.

Explanation:

α = `Λ/(Λ_∘) = 6/400`

K_a = α²C

= `6/400 xx 6/400 xx 1/36`

= 6.25 × 10⁻⁶