Advanced Topic 938 of 1102 Analytical, Lab & Spectroscopy
Potentiometric Titration
Equivalence point detected by following electrode potential.
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In-depth explanation of Potentiometric Titration
Potentiometric titration follows the potential of an indicator electrode, often a glass pH electrode or a metal electrode, measured against a stable reference electrode as titrant is added. The potential changes most rapidly at the equivalence point, which is located at the inflection of the titration curve or at the maximum of the first derivative of potential with volume. The method does not rely on a colour indicator, so it works well for coloured, turbid or dark solutions where visual endpoints are unreliable. It can be automated and gives an objective endpoint. The Nernst equation links the measured potential to the activity of the species being titrated.
Going deeper: Potentiometric Titration
Key ideas: Plot E (or pH) versus volume, then first derivative delta E/delta V against average volume to find the maximum, or second derivative crossing zero. Glass electrode needs calibration with two buffers (such as pH 4 and 7) and response is about 59 mV per pH unit at 25 C. For a weak acid, pH at half equivalence equals pKa, giving a direct measure of acid strength.
Common mistakes and connections: Students forget to rinse and calibrate electrodes, or add titrant too fast near equivalence so the reading lags. A dry or damaged glass membrane gives drifting readings. Reading the equivalence point at pH 7 for a weak acid-strong base titration is wrong because it lies above 7. Related to Nernst equation, pH curves, buffers and reference electrodes.
Visualization of Potentiometric Titration
A weak acid with pKa 4.76 titrated by NaOH gives a pH curve whose steepest point, the maximum of the first derivative, marks equivalence without an indicator. The interactive lesson shows this as a live animation or chart.
Worked example and use case
The equivalence point of a weak acid titrated with sodium hydroxide is located from the maximum of the first derivative of the pH curve.
Frequently asked questions about Potentiometric Titration
What is Potentiometric Titration?
Equivalence point detected by following electrode potential.
Is Potentiometric Titration a beginner, intermediate or advanced topic?
Potentiometric Titration is a advanced topic in Analytical, Lab & Spectroscopy. It builds on beginner and intermediate topics, so review those first if needed.
What should I learn before Potentiometric Titration?
Study these earlier topics in Analytical, Lab & Spectroscopy first: Back Titration, Redox Titrations, Complexometric Titration.
What comes after Potentiometric Titration?
The next topics in Analytical, Lab & Spectroscopy are Conductometric Titration and Error Analysis.
Can I practise Potentiometric Titration with quizzes?
Yes. The interactive lesson includes a self-check question on Potentiometric Titration, and the Analytical, Lab & Spectroscopy quiz draws on every topic in this area.
Where Potentiometric Titration fits in Analytical, Lab & Spectroscopy
Potentiometric Titration is topic 62 of 99 in Analytical, Lab & Spectroscopy.