The key difference between KF and coulometer is that in the KF method, the titrant is added directly to the sample using a burette, whereas in the coulometer, the titrant is generated electrochemically in the titration cell.
KF and coulometer are two analytical instruments. These instruments are named according to the titration technique.
CONTENTS
1. Overview and Key Difference
2. What is KF
3. What is Coulometer
4. KF vs Coulometer in Tabular Form
5. Summary – KF vs Coulometer
What is KF?
KF or Karl Fischer titration is a type of classic titration technique that uses coulometric or volumetric titration to determine trace amounts of water in a sample. This technique was first invented in 1935 by the German Chemist Karl Fischer. At present, this method is carried out using an automated Karl Fischer titrator.
When considering the chemical principle of this technique, the elementary reaction that is responsible for water quantification in the Karl Fischer titration is the oxidation of sulfur dioxide with iodine. This reaction consumes only one molar equivalent of water with iodine. The iodine has to be added to the solution until it comes to an excess limit. This marks the end point of the titration, and we can detect this point using potentiometry. Moreover, the reaction happens in the presence of an alcohol solution consisting of a base that can consume the sulfur trioxide and hydroiodic acid that is formed intermediately.
What is Coulometer?
A coulometer is an instrument used for chemical analysis that can determine the amount of a substance that is released in electrolysis through the measurement of the quantity of electricity that is used. For example, a silver coulometer is an instrument used to determine the mass of silver deposited at a platinum cathode via the passage of an electric current in the presence of an aqueous silver nitrate solution.
There are two types of coulometry: controlled potential coulometry and amperostatic coulometry. In the controlled potential coulometry, we can use a three-electric potentiostat to set the potential. Whereas, the amperostatic coulometry keeps the current constant using an amperostat, which is measured in amperes.
Furthermore, potentiostatic coulometry can be described as a technique that is most commonly referred to as “bulk electrolysis.” It has a working electrode kept at a constant potential where the current flowing through the circuit can be measured. We can apply this potential to a length that is enough to reduce or oxidize all the electroactive species completely in a given solution.
What is the Difference Between KF and Coulometer?
The key difference between KF and coulometer is that in the KF method, the titrant is added directly to the sample using a burette whereas, in the coulometer, the titrant is generated electrochemically in the titration cell. Moreover, a KF titration measures the water content in a variety of products, while the coulometer measures the amount of electricity consumed or produced. In addition, a KF is a volumetric technique, whereas a coulometer is a coulometric technique.
Below is a summary of the difference between KF and coulometer in tabular form for side-by-side comparison.
Summary – KF vs Coulometer
KF titration is a type of classic titration technique that uses coulometric or volumetric titration to determine the trace amounts of water in a sample. A coulometer is an instrument used for chemical analysis that can determine the amount of a substance that is released in electrolysis through the measurement of the quantity of electricity that is used. The key difference between KF and coulometer is that in the KF method, the titrant is added directly to the sample using a burette, whereas in the coulometer, the titrant is generated electrochemically in the titration cell.
Reference:
1. “Coulometers.” An Overview | ScienceDirect Topics.
Image Courtesy:
1. “Test de capacité – Montage du coulomètre” By Goelette Cardabela – Own work (CC BY-SA 4.0) via Commons Wikimedia