Question

Consider the equilibrium HClO3(aq) <----> ClO3-(aq) + H+(aq). If the equilibrium constant Kc is 10.0, and the initial concentration of HClO3 is 1.00 M, calculate the equilibrium concentration of H+ .
3.16
10.0
0.916 M
10.9 M

Answer 1

The reaction is

                           HClO3(aq) <----> ClO3-(aq) + H+(aq).

Concentrations

Initial                      1                             0                0

Change                    -x                         +x              +x

Equilibrium              1-x                         x                 x

Kc = [ClO3-] [ H+] / [HClO3] = x^2 / 1-x = 10

10 - 10x  = x^2

x^2 + 10x - 10x = 0

On solving

x = 0.916 M

so equilibrium concentration of H+  = x = 0.916 M