Question

Calculate pH and concentration of H2SO3, H2SO3- and SO32- in NaHSO3 c=0,05M.

Ka1= 1,23*10^(-2)
Ka2= 6,6*10^(-8)

Results attached are:
a) [H2SO3]= 1,04x10-4 M,
[SO32-]=1,3x10-4 M,
[HSO3-]= 0,05 M

but i keep getting different numbers.

Answer 1

What do you mean by "results are attached"? Are those the answers in the key or your answers.

Check you typo. H2SO3- should be HSO3^-.

..........NaHSO3 ==> Na^+ + HSO3^-
I..........0.05.......0......0
C........-0.05.......0.05....0.05
E..........0.........0.05....0.05

........HSO3^- ==> H^+ + SO3^2-
I.......0.05.......0......0
C.......-x.........x......x
E......0.05-x......x......x

k1 = (H^+)(SO3^2-)/(HSO3^-)
Substitute the E line and solve for x. You will need to solve the quadratic.
(H^+)=(SO3^2-) = about 0.0192 M
and (HSO3^-) = 0.05-0.0192 = ?

Answer 2

Are you supposed to use the quadratic formula? Given that C> 100Ka?