(8.a) pH 1.54
| NaHSO4 | Na+ | + | HSO4- |
| 0.10 M | 0.10 M |
This salt dissociates completely. The anion HSO4- is a weak acid and it can dissociate faster.
| HSO4- | <---> | H+ | + | SO4-2 | |
| Initial (I) | 0.10 M | 0 M | 0M | ||
| Change (C) | -x | +x | +x |
| Equilibrium(E) | (0.10 - x)* | x | x |
*Hint: since [HSO4-] < 100 Ka then (0.10 - x) is not = 0.10
Ka = {[ H+][ SO4-2]}/[ HSO4-]
1.2 x 10-2 = {(x)(x)}/(0.10 - x )
x2 = 1.2 x 10-2(0.10 - x)x2 = 1.2 x 10-2x - 1.2 x 10-3 = 0 Use the quadratic formula
a = 1
b = 1.2 x 10-2
c = 1.2 x 10-3
x = {+ b2 - 4ac}/2a
x = {- 1.2 x 10-2 + 4.8 x 10-3}/2
x = {- 1.2 x 10-2 + 0.07}/2
x = 0.029 OR.... x = - 0.81 (not valid)
pH = - 1og [H+]
pH = - log 0.029
pH = 1.54