Diprotic acids

Definition

Diprotic acids are acids that can donate two protons (hydrogen ions) per molecule in a reaction. They undergo two dissociation steps, each with its own equilibrium constant.

5 Must Know Facts For Your Next Test

1. Diprotic acids have two dissociation constants: $K_{a1}$ for the first dissociation and $K_{a2}$ for the second.
2. Common examples of diprotic acids include sulfuric acid ($H_2SO_4$) and carbonic acid ($H_2CO_3$).
3. The first dissociation step of a diprotic acid usually occurs more readily than the second due to higher acidity.
4. In aqueous solutions, diprotic acids can form intermediate species such as $HSO_4^-$ or $HCO_3^-$.
5. Calculations involving diprotic acids often require solving quadratic equations to find pH and concentration of species.

Review Questions

Related terms

Monoprotic Acid: An acid that can donate only one proton per molecule in a reaction.

$K_a$ (Acid Dissociation Constant): $K_a$ is a measure of the strength of an acid in solution, representing the equilibrium constant for its dissociation into ions.

Polyprotic Acid: An acid capable of donating more than one proton per molecule, including diprotic and triprotic acids.