1. When Kb1 > 100 Kb2, treat the diprotic system as if it was a
monoprotic base (assume the contribution from the second
protonation on pH is negligible!)
A2- + H2O HA- + OH-
2. Solve the equation:
where [OH-] = [HA-] = x,
Introduction to titrations
Quantitative Chemical Analysis
Purpose? To determine the unknown concentration of
one or more components of interest in a sample
What does it mean?
pH = pKa + log(
If you know:
1. the ratio of [A-]/[HA] of weak acid and its conjugate base
2. The Ka
Know the pH of that solution!
Note, if you prepare a buffer by adding a weak
acid HA and its
Polyprotic Acid-Base Equilibria
Polyprotic Acids and Bases
Polyprotic acids and bases can donate or accept more than one proton.
-can have diprotic systems, triprotic systems, etc
Examples: Diprotic acids can donate two protons
e.g. H2SO4, H2CO3, H2C2O