Diprotic Basic Buffer
For a typical diprotic base buffer system you can use sodium bicarbonate. Adding hydrochloric acid to sodium carbonate solution

The overall equation for the reaction between sodium carbonate solution and dilute hydrochloric acid is:

$$\ce{Na2CO3(aq) + 2HCl(aq) -&gt; 2NaCl(aq) + CO2(g) + H2O(l)}$$

If you had the two solutions of the same concentration, you would have to use twice the volume of hydrochloric acid to reach the equivalence point - because of the 1 : 2 ratio in the equation

Take a look at he sample titration curve:



The sense of diprotism of a base, is revealed through its ability to accept the two protons from hydrochloric acid to form water.

Referencing and diagrams from


pH (TITRATION) CURVES