Question

Determine the concentrations of the following ionic species present in a 0.293 M solution of the diprotic acid H2SO3. For H2SO3, Ka1 = 1.4E-2, Ka2 = 6.3E-8.

What is the H3O+ ion concentration?

What is the HSO3- ion concentration?

What is the SO32- ion concentration?

Answer 1

H2SO3   ---------------> H+ + HSO3-

0.293                             0            0

0.293 - x                        x             x

Ka1 = x^2 / 0.293 - x

1.4 x 10^-2 = x^2 / 0.293 - x

x = 0.0574

[H3O+] = 0.0574 M

[HSO3-] = 0.0574 M

[SO32-] = 6.30 x 10^-8 M