Introduction to Redox Titrations
Unit 4 focuses on Oxidation-Reduction (Redox) titrations. These involve the transfer of electrons between the analyte and titrant. You will study various types of oxidizaing agents like Iodine (Iodometry/Iodimetry), Cerium (Cerimetry), Dichromate, and Bromate, and their specific applications in drug analysis.
Syllabus & Topics
- 1Concepts of Oxidation and Reduction
- 2Types of Redox Titrations: Principles and Applications
- 3Cerimetry: Principle, Indicator (Ferroin), Application
- 4Iodimetry: Direct titration with Iodine
- 5Iodometry: Indirect titration (Liberation of Iodine)
- 6Bromatometry: Use of KBrO3 (Oxidizing agent)
- 7Dichrometry: Use of K2Cr2O7
- 8Titration with Potassium Iodate (KIO3)
Learning Objectives
Frequently Asked Questions (FAQs)
Q1. What is Cerimetry?
Cerimetry is a type of redox titration that uses Cerium (IV), usually in the form of ammonium ceric sulfate, as a strong oxidizing agent in an acidic medium. Ferroin is the commonly used indicator.
Q2. Why is Sodium Thiosulphate standardized against Potassium Dichromate?
Sodium thiosulphate is not a primary standard because it is unstable. Potassium dichromate, a primary standard, liberates iodine from potassium iodide in acidic medium. The liberated iodine is then titrated with sodium thiosulphate to standardize it.
Q3. What is the principle of Bromatometry?
Bromatometry uses potassium bromate (KBrO₃) as an oxidizing agent. In acidic medium, bromate reacts with bromide to release free bromine, which then reacts with the analyte (such as phenol) or is back-titrated.
Q4. What is Starch Indicator?
Starch is used as an indicator in iodometry and iodimetry. It forms a deep blue complex with free iodine. The appearance or disappearance of the blue color indicates the end point.
Q5. What is Dichrometry?
Dichrometry involves titration using potassium dichromate (K₂Cr₂O₇) as an oxidizing agent in an acidic medium. It is commonly used for the estimation of ferrous ions (Fe²⁺).