Question

Determine the pH of a 0.45M solution of Na2SO3 where Ka1 = 1.5 x 10^(-2) and Ka2 = 6.3 x 10^(-8).

Answer 1

..................SO3^2- + HOH ==> HSO3^- + OH^-
I.................0.45..........................0..................0
C................-x.............................x...................x
E..............0.45-x........................x...................x

Kb1 for SO3^2- = (Kw/Ka2 for H2SO3) = (x)(x)/(0.45-x)

Solve for x = (OH^-) and convert to pH.
Post your work if you get stuck.