Acid-Base Titrations

Interpreting Titration Graphs

Titration graphs visualize the change in pH as titrant is added to the unknown solution. 

Equivalence Point: The inflection point of the graph, shows when moles of H₃O⁺ equal the moles of OH⁻. 

Halfway Point: Half of the volume of titrant added at equivalence. For weak acids, this point indicates that [HA] = [A⁻]. 

• pH = pKa + 0 at the halfway point. (According to the Henderson-Hasselbalch equation.)

• This property doesn't apply to strong acids, as they completely dissociate. ([A⁻] effectively equals 0.)

  • For weak acids, this is the ideal region to create a buffer as both the 

Titrations with...

• Strong Acid-Strong Base: Equivalence point occurs at a pH of 7 as a result of the titrant completely neutralizing the solution. Produces water, a neutral salt, and nothing else. Strong acids and bases both have pH values that largely deviate from 7. 

• Weak Acid-Strong Base: Equivalence point occurs at a pH of above 7. After neutralization, the conjugate base of the acid continues accepting protons, indirectly producing OH⁻. Weak acids have a higher pH than strong acids of the same molarity.