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An oxidation-reduction reaction between an oxidising agent and a reducing agent is known as redox titration. The chemical reaction occurs in this form of titration when electrons are transferred between reacting ions in aqueous solutions.
A reducing material is titrated with a standard solution of an oxidising agent, or an oxidising substance is titrated with the standard solution of the reducing agent in the oxidation-reduction titration method.
A redox indicator and/or a potentiometer may be used in a redox titration. Treating an iodine solution with a reducing agent to make iodide while employing a starch indicator to aid in identifying the endpoint is a popular example of redox titration.
What are the principles of redox titration?
The amount of oxidising or reducing agent used to titrate the unknown species is measured in a redox titration. The redox titration is carried out by adding a known amount of oxidising or reducing agent to a sample of the unknown species and then measuring the oxidising or reducing agent’s concentration change. The unknown species’ concentration is calculated using the change in concentration.
Redox Titration Curve
We need to know the form of the titration curve of a redox titration to evaluate it. The complexation titration shows the way in which H₃O⁺ (as pH) or Mn+ fluctuates as titrant is added. It is more convenient to monitor the titration reaction’s potential rather than the concentration of one species in a redox titration.
Redox Titration Examples
Titration can be used to track and measure a species’ oxidation and reduction. The addition of thiosulfate (S2O3²–) to the solution, for example, can be used to monitor the oxidation of iodide (I–) to iodine (I2). Iodine will be reduced to iodide by the thiosulfate. The titration’s endpoint can be calculated by adding a starch indicator to the solution. When the blue starch indicator comes into touch with the iodine, it turns red.
Theory of redox indicators
A redox indicator is a molecule that changes colour when potential differences are changed. Colourimetric reagents that show a particular colour shift at a specific electrode potential are known as oxidation/reduction (redox) indicators. These are all reversible redox reactions in organic molecules. Nile blue, Anilinic acid, diphenylamine, eriogreen, m-cresol-indophenol, and methylene blue are among the examples.
The reduced and oxidised forms of a redox indicator molecule must exhibit different hues, and the redox process must be reversible. Furthermore, the oxidation-reduction equilibrium must be swiftly achieved. Redox indicators are only suitable for a few types of compounds:
In these titrations, free iodine is reduced to iodide ions, and iodide ions are oxidised to free.
l2 + 2e– → 2l–……………. (reduction)
2I– → I2 + 2e– ……………. (oxidation)
As an indicator, the solution is utilised. The iodometric titration uses free iodine, whereas the iodometric titration uses an oxidation agent to react and liberate free iodine.
Purpose of redox titration
Calculating an Analyte’s Concentration: A redox titration (also known as an oxidation-reduction titration) can correctly measure the unfamiliar analyte by measuring it against a standardised titrant, similar to an acid-base titration.
Also, what exactly is redox titration, and what are the principles of redox titration? A titrant solution of known concentration is added to an analyte solution until just enough has been added to react with all of the analyte (the equivalence point). The process is known as redox titration when the interaction between the titrant and the analyte involves a reduction-oxidation reaction.
Applications of Redox Titration in Chemistry
It is widely used to estimate medium and high element concentrations. Furthermore, even in field situations, titration provides trustworthy findings. A wide spectrum of inorganic analytes is studied using redox titrimetry. By testing an unknown analyte against a standardised titrant, a redox titration (also known as an oxidation-reduction titration) can correctly establish its concentration.
Applications of the principles of Redox Titration in Pharmacy
- In the healthcare industry, redox titration is used to determine the concentration of valganciclovir hydrochloride in tablets.
- Two spectrophotometric approaches that are simple, selective, and sensitive have been devised and verified.
- The first approach used VLGH to reduce iron(III) to iron(II) and then generate an iron(III)-ferricyanide complex (Prussian blue) in an acid solution, which was detected at 730 nm (method A).
- VLGH converted permanganate to bluish green manganate in alkaline media in the second procedure (method B), and the absorbance was measured at 610 nm. In each example, the absorbance was related to the concentration of VLGH.
Conclusion
Just like acid-base titrations, a redox titration can correctly compute the concentration of an unknown analyte by measuring it against a standardised titrant. Photosynthesis, respiration, combustion, and corrosion or rusting are all examples of redox reactions that are common and essential to life.
