H2SO3 <----------------------> H+ + HSO3-
25Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
0Â Â Â Â Â Â Â Â
0Â Â Â ---------------> initial
25-x                                     Â
x         x
---------------> equilibrium
Ka1 = [H+][HSO3-]/[H2SO3]
Ka1 = x^2 / 25-x
1.4 x 10^-2 = x^2 / 25-x
x^2 + 1.4 x 10^-2 x - 0.35 = 0
x = 0.585
[H+] = 0.585 M
[HSO3-] = 0.585 M
pH = -log [H+]
pH = 0.233
[H2SO3 ] = 25 -0.585
[H2SO3 ]Â Â Â = 24.4 M
[SO3-2] = Ka2 =
6.3×10–8
