Karl Fischer titration: What is it?
Karl Fischer titration is a volumetric or coulometric titration technique that determines the water concentration in an analyte. The German chemist Karl Fischer developed this quantitative chemical analysis technique in 1935. Such titrations can be performed by special titrations, also known as Karl Fischer titrations.
Principles of Karl Fischer titration
Karl Fischer's titration is based on the sulfur dioxide and iodine oxidation reaction. Sulfur trioxide and hydrogen iodide are produced during the production of water. , iodine, and sulfur dioxide combine. The process ends when the last drop of water has been consumed. The chemical formula for Karl's reaction is used when combined with sulfur dioxide, iodine, and water.
I2 + SO2 + H2O → 2HI + SO3
Karl Fischer titration apparatus
Drying tube, rotor, anode chamber, drain soup, electrode analysis, sample injection chamber, cathode chamber, and KF reagent.
KF -reactive ingredients:
Iodine, sulfur dioxide, solvent (methanol), and buffer (imidazole).
Karl Fischer titration method
There are two ways to do the Karl Fischer titration. They are as follows:
Volume determination:
This method effectively determines water content up to 1%. Iodine is added to the KF reagent after dissolving the sample in KF methanol. Potentiometric detection is used to find the end-point.
Coulometric determination:
In this experiment, the end-point is found electrochemically. Iodide in solution is oxidized anodically to produce iodine, which is needed for the KF reaction.
Applications of Karl Fischer Titration
- It is used in technical products such as gases, oils, and plastics.
- It is used in pharmaceutical products.
- Products are used in cosmetics.
- It is used in industry.
Karl Fischer titration is a reliable and robust method routinely used for direct water content analysis in many companies. It is used in the food industry to ensure the water content of natural products, juices, honey, flour, noodles, packages, and
The oil industry uses many different oils, fuels, lamp oils, and gasoline. The surface industry ensures the water content of shampoos, creams, lipsticks, and toothpaste. It is used to provide water in materials used in construction, such as silk, wool, wood, paper, and, surprisingly, zeolite and concrete.
According to the needs and nature of the customer, Karl has a wide range of Fischer reagents. Titration is available. Also, ethanol can be used instead of methanol as a "greener" solvent, and imidazole can be replaced by pyridine as an essential (and less offensive) base.
The advantages of Karl Fischer titration
- It can measure the amount of water in solids, liquids, and gases.
- A coulometric titration device facilitates the detection of free, dissolved, and emulsified water.
- Very accurate technology.
- It helps determine the location of water in gases, liquids, and solids.
- Coulometric titration facilitates free, dissolved, and emulsion water detection.
- The high solvent consumption of manual volumetric titration is due to the need to recharge—the device after each measurement.
- This rapid procedure requires little sample preparation.
- It is an exceptional method.
- Tests suitable for coulometric titration require that the samples contain very little water.
Limitations of Karl Fischer titrations
- It is a destructive technique.
- The solvent consumption is high because manual volumetric titrations require recharging during each determination.
- Coulometric titrations are adapted for samples that contain only a tiny amount of water.
- Colometric titration takes a very long time.
Frequently Asked Questions
Q1. What methanol is used in Karl Fischer's Titration?
In the Karl Fischer titration, methanol serves as the solvent.
Q2. How can a KF reagent be prepared?
Prepare a solution by mixing 170 mL of pyridine and 670 mL of methanol. 125 g of iodine is added to the solution and cooled. Take a 250 ml measuring cylinder and add 100 ml of pyridine. Could you keep it in an ice bath? Add sulfur dioxide (dry) until the volume is 200 mL.
Q3. What is the main difference between volumetric and coulometric titrations?
The primary distinction between the two is:
Volume method: The titrant is added straight to the sample using a buret.
The titrant used in the coulometric method is generated electrochemically in a titration chamber.
Q4. What is coulometric Karl Fischer?
Karl Fischer titration is just a tool to measure the water content of a sample. Modern devices, like the Aquamax KF, employ the coulometric principle, where the water in the sample is coulometrically titrated to a predetermined end-point where the amount of free iodine exceeds one minute.
Q5. Why do we use sodium tartrate in Karl Fischer?
Sodium tartrate dihydrate serves as the volumetric standard for Karl Fischer titration. Under typical circumstances, it is non-hygroscopic and stable. Sodium tartrate dihydrate has a stoichiometric water content of 15.66 percent and is primarily used in volumetric titration.
Q6. Which electrode is used for KF titration?
The abundance of iodine has caused the reaction to reach its termination point. Although visual and photometric indications are still utilized, the most sophisticated KF titration technology employs a double platinum electrode for electrochemical end-point indication.
Q7. How is the Karl Fischer factor calculated?
The formula for calculating the water equivalency factor F is 0.1566 x w / v in mgs of H2O per ml of reagent, where W is the weight of sodium tartrate in mgs and V is the reagent volume in milliliters.
Q8: How is Karl Fischer reagent made?
The reagents are solvent alcohol (ROH), sulfur dioxide (SO2), a base (RN), and an established concentration of iodine (I2). In an aqueous environment,
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