What is a redox titration? Redox titration is a method of analyzing the reduction and oxidation reactions that occur between the titrant (a substance whose concentration is known) and the titrate (a substance whose concentration will be revealed by titration). In contrast to acid-base titrations, complexometric titrations, and precipitation titrations, you need to know the ins and outs of redox titrations that have been applied in various industries. The following is a complete explanation.
Principles of Redox Titration
Redox titration is short for reduction and oxidation titration. Reduction is the process of taking electrons in an atom, ion, or molecule. Conversely, oxidation is the process of liberating an electron from an atom, ion, or molecule. In fact, oxidation is always followed by reduction, so there is a redox reaction.
In a redox reaction, the number of electrons freed is always the same as the number of electrons taken up. When compared to acid-base reactions, the concept is quite similar in that the number of protons liberated by the acid is always the same as the number of protons taken up by the base. Redox titration occurs when there is a transfer of electrons between the titrant and the titrate. Since redox reactions generally occur in water, it is necessary to equalize the coefficient of the water reaction using H + or OH-.
A redox reaction can only be used as the basis for a titration if it meets the following requirements:
1. The redox reaction must be rapid and nearly complete (<99% success is intolerable).
2. The end point must be measurable or detectable, either by means of a color indicator or potentiometry.
3. The process for the exchange of electrons must be stoichiometric, meaning that the pairs of redox systems (oxidizing and reducing agents) are appropriate and equal.
Also read: Definition, How it Works, and Types of Acid-Base Titration
Types of Redox Titration
In practice, redox titration is carried out by carrying out a quantitative analysis of the reaction between oxidizing compounds and reducing compounds. Therefore, redox titration is also divided into several types based on the nature of the standard solution, namely oxidimetry and reduximetry. Here's the explanation.
1. Permanganometry
As the name implies, this type of redox titration uses potassium permanganate (KMnO4) as the titrant and oxidizer. For permanganometry, you can use an acid such as dilute H2SO4 or HClO4 but Cl- has the potential to be oxidized and has limited stability. When using a colorless solution, permanganometric titration does not require an indicator because a drop of 0.1 N permanganate shows a purplish-pink color in 100 ml of solution.
2. Dichromatometry
Dichromatometry uses dichromate (Cr2O7) which is a strong oxidizing agent, but is still under permanganate. In the process, the dichromate ion is then reduced to Cr3 + which has a green color. Dichromate was chosen because of its good stability and pure form. Unfortunately, dichromate has a fairly slow reaction.
3. Iodometry and iodimetry
Iodimetric and iodometric titrations are redox titrations that use iodine. Iodometry is an indirect titration that uses iodine as a reducing agent, where the released iodine is titrated using a thiosulfate solution. Meanwhile, iodimetry is a direct titration that is carried out under conditions of neutral or slightly acidic pH, where iodine is used as an oxidizing agent.
4. Bromatometry
Bromatometry uses potassium bromate (KBrO3) as a reducing agent and titrant. To speed up the reaction, bromatometry is usually carried out in hot temperatures and acidic pH conditions. Excess KBr will cause a reaction on the bromate ion which then produces a pale yellow color that is difficult to determine as an end point.
Also read: Understanding Potentiometric Titration and Its Functions
Redox Titration Applications
Obviously you will want to know under what conditions or purposes the redox titration is performed in the laboratory. In fact, redox titrations are common for the carbohydrate test, the vitamin C test, the winkler test, and the Karl Fischer titration. Obviously, here are some applications of redox titration for a number of industries around us:
In the pharmaceutical industry, redox titration is performed to analyze the amount of vitamin C content in a drug sample. This is because vitamin C is a good reducing agent.
In the alcoholic beverage industry, a redox titration is performed to analyze the levels of sulfate in wine using iodine. Redox titration can also determine the alcohol content of a drink using potassium dichromate.
In the food industry, redox titration can be used to see the quality of used cooking oil, namely by looking at peroxide levels.
That's important information regarding redox titration that you can learn. If your business wants to perform redox titration for the sake of product procurement or quality control, make sure you already have a quality titration tool that is able to provide convenience and accuracy. Hopefully the information about redox titration above is helpful!
Also read: How to Use Karl Fischer Titration You Need to Understand
