Question

A) Calculate the concentration of all species in a 0.490 M solution of H2SO3.

B) Calculate the concentration of all species in a 0.165 M solution of H2CO3.

Answer 1

A)

H2SO3 ----------------> H+ + HSO3-

0.490                              0          0

0.490 - x                          x           x

K_a1 = 1.4×10^–2

Ka1 = x^2 / 0.490 - x

1.4 x 10^-2 = x^2 / 0.490 - x

x = 0.0761

[H+] = [HSO3-] = 0.0761 M

[SO32-] = K_a2 = 6.3×10^–8 M

[H2SO3] = 0.490 - x = 0.414 M

[OH-] = 1.314 x 10^-13 M

B)

H2CO3 ---------------> H+ + HCO3-

0.165                           0           0

0.165 - x                      x            x

Ka1 = x^2 / 0.165 - x

4.5×10^–7 = x^2 / 0.165 - x

x = 2.72 x 10^-4

[H+] = [HCO3-] = 2.72 x 10^-4 M

[CO32-] = Ka2 = 4.7×10^–11 M

[H2CO3] = 0.165 - x = 0.1647 M

[OH-]= 3.68 x 10^-11 M