When does pH equal pKa?
Understand the Problem
The question is asking when the pH of a solution is equal to its pKa value, which typically occurs at the midpoint of a buffer solution where half of the acid is dissociated. This relates to acid-base chemistry and the Henderson-Hasselbalch equation.
Answer
at the half-equivalence point
The final answer is at the half-equivalence point
Answer for screen readers
The final answer is at the half-equivalence point
More Information
At the half-equivalence point during a titration of a weak acid with a strong base (or vice versa), the acid and its conjugate base have equal concentrations. This is described by the Henderson-Hasselbalch equation, where pH = pKa.
Tips
A common mistake is to assume that pH = pKa at the equivalence point, which is not correct. The equivalence point is when the moles of titrant are equal to the moles of the substance being titrated.
Sources
- When is the pH equal to the pKa value? - Quora - quora.com
- Why does pH=pKa at the halfway titration point? - Laurence Lavelle - lavelle.chem.ucla.edu
- 17.3: Acid-Base Titrations - Chemistry LibreTexts - chem.libretexts.org
