The key difference between volumetric and potentiometric titration is that volumetric titration measures the volume of the analyte reacted with the reagent, whereas potentiometric titration measures the potential across the analyte.
Titrations are chemical techniques used to identify the amount of an unknown compound present in a given mixture. In this technique, we use a solution of a known concentration to find the concentration of an unknown present in our sample.
CONTENTS
1. Overview and Key Difference
2. What is Volumetric Titration
3. What is Potentiometric Titration
4. Side by Side Comparison – Volumetric vs Potentiometric Titration in Tabular Form
5. Summary
What is Volumetric Titration?
Volumetric titrations are analytical techniques that measure the volume of the analyte that reacts with a reagent having a known concentration. In this technique, we can use a solution having a known concentration to find the concentration of an unknown present in our sample. Here, the point where all the analyte molecules completely react with reagent molecules is called the endpoint. Therefore, the endpoint indicates the end of the reaction between the unknown compound and the known compound. Volumetric titrations can be done in various ways. Back titrations and direct titrations are two such types.
Figure 01: Titration Apparatus
A direct titration is the basic titration method that involves the reaction between the unknown compound and the compound with known concentration. Here, the addition of excess reagents is not done like in back titrations. The unknown compound is directly reacted with the known compound. Therefore, the endpoint of the titration indicates the end of the reaction. By using that endpoint, the amount of unknown compound present in the sample solution can be determined.
A back titration is useful in determining the concentration of an unknown using an excess amount of a compound with a known concentration. Since the amount of the compound with a known concentration added is known already, we can determine the amount of the compound that has reacted with the unknown compound by doing a back titration.
What is a Potentiometric Titration?
A potentiometric titration is an analytical technique that can be used to measure the potential across the analyte. Here, an indicator is not required to determine the endpoint of the titration. However, this type of titrations is very similar to redox titrations.
Figure 02: Apparatus for Potentiometric Titration
In the titration apparatus, there are two electrodes. They are named as indicator electrode and reference electrode. Usually, we use glass electrodes as indicator electrodes and hydrogen electrodes, calomel electrodes and silver chloride electrodes as reference electrodes. The indicator electrode is important in monitoring the endpoint of the titration. At the endpoint, a sudden and huge change of potential occurs.
There are some advantages of using this technique; e.g. it does not require an indicator and is far more accurate than a manual titration. There are several types of potentiometric titration techniques that provide us with a great variety of options depending on the need. Moreover, this type of titrations works well with automated systems.
What is the Difference Between Volumetric and Potentiometric Titration?
Titrations are chemical techniques used to identify the amount of an unknown compound present in a given mixture. The key difference between volumetric and potentiometric titration is that volumetric titration measures the volume of analyte reacted with the reagent, whereas potentiometric titration measures the potential across the analyte. Moreover, volumetric titrations are easy and quick when compared to potentiometric titrations.
Below infographic summarizes the difference between volumetric and potentiometric titration.
Summary – Volumetric vs Potentiometric Titration
Titrations are chemical techniques used to identify the amount of an unknown compound present in a given mixture. The key difference between volumetric and potentiometric titration is that volumetric titration measures the volume of analyte reacted with the reagent, whereas potentiometric titration measures the potential across the analyte.
Reference:
1. “Titration.” Chemistry LibreTexts, Libretexts, 23 June 2019, Available here.
2. “Titration.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 6 Oct. 2017, Available here.
Image Courtesy:
1. “Acid and Base Titration” By Kengksn – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Potentiometric Titration Apparatus” (CC0) Free SVG