Question

If the initial concentration of an acid in solution is 2.30 M, and the solution has a pH=3.40 at equilibrium, what is the percent ionization of the acid?

Answer 1

use:

pH = -log [H+]

3.4 = -log [H+]

[H+] = 3.981*10^-4 M

HA       <—>   H+       +   A-

2.30           0           0       (initial)

2.30-x           x           x       (at equilibrium)

so,

x = [H+] = 3.981*10^-4

% dissociation = x*100/c

= (3.981*10^-4)*100 / 2.30

= 0.0173 %

Answer: 0.0173 %