# Exercise 5 | The Properties of Acids and Bases

The pH of a 4.0 x 10-2 M of formic acid HCOOH is 3.08. Calculate the % dissociation of HCOOH.

% dissociation = $\frac{\left[{\mathrm{H}}_{3}{\mathrm{O}}^{+}\right]}{{\left[\mathrm{HCOOH}\right]}_{0}}$ x 100

[H3O+] = 10-pH = 10-3.08 = 8.32 x 10-4 M

[HCOOH]0 = 4.0 x 10-2  M

% dissociation =  x 100 = 2.1 %