What are the equilibrium concentrations of H2SO3, H+, HSO3−, and SO32−in a 0.050 M solution of sulfurous acid H2SO3 at 25 oC? For H2SO3 at 25 oC, Ka1 = 1.5×10−2 and Ka2 = 1.0×10−7

Answer 1

.......H2SO3 ==>H^+ + HSO3^-
I......0.05......0......0
C.......-x.......x.......x
E....0.05-x......x.......x

k1 = (H^+)(HSO3^-)/(H2SO3)
Substitute and solve for x = (H^+).
That gives you (H^+), (HSO3^-) and (H2SO3)

.........HSO3^- ==> H^+ + SO3^2-

k2 = (H^+)(SO3^2-)/(HSO3^-). Since (HSO3^-) = (H^+), the (SO3^2-) = k2.