"Published in Newark, California, USA"
When 0.02 moles of a monoprotic acid is dissolved in 350 mL of water, the pH is 3.05. What is the ionization constant of this acid?
Solution:
Monoprotic acid is an acid which donates one electron during the ionization process. Monoprotic acid can be an inorganic acid or organic acid as long as one electron is lost during the ionization process.
If the pH of an acid is 3.05, then the concentration of hydrogen ion is
Let's assume that the volume of water is equal to the volume of a solution because the amount of a monoprotic acid is very small or negligible. The concentration of a monoprotic acid at the start of ionization process is
Since the concentration of [H+] is very small compared with [HA], then HA is a weak acid. The ionization of HA is written as follows
Therefore, the ionization constant of a monoprotic acid is
