Question

Find the ClO− concentration of a mixture that is 0.340 M in HF and 0.100 M in HClO.

Answer 1

Determine the concentration of H3O+

Balanced equation with ICE table

HF + H2O = H3O+ + F-

I 0.340

C - x    +x +x

E 0.340-x x x

Equilibrium constant expression of the reaction

K = [H3O+] [F-] / [HF]

3.5 x 10^-4 = x² /( 0.340-x)

0.000119 - 0.00035x - x² = 0

x = 0.010735 = [H3O+]

Dissociation reaction of HClO

HClO + H2O = H3O+ + ClO-

I 0.1 0.010735

C - x +x +x

E 0.1-x 0.010735+x x

Equilibrium constant expression of the reaction

K = [H3O+] [ClO-] / [HClO]

3 x 10^-8 = (0.010735+x)(x)/(0.1-x)

3 x 10^-8 x 0.1 = 0.010735 x

x = 2.79 x 10^-7

[ClO-] = 2.79 x 10^-7 M