VOLUMETRIC ANALYSIS
What is Volumetric Analysis:
Volumetric analysis is a laboratory method used to determine the quantity of a chemical present in a solution by measuring the volume of a standard solution required to react completely with it.
This method is also known as titrimetric analysis, and the process is called titration. It is widely used in chemistry and pharmaceutical laboratories.
Common apparatus used: Burette, pipette, volumetric flask, conical flask, measuring cylinder.
Fundamentals of Volumetric Analysis:
- Analyte contains unknown amount of substance
- Standard solution reacts with analyte
- Indicator shows endpoint by colour change
- Reaction completes at equivalence point
- Volume and concentration are used to calculate unknown amount
- Chemical equation determines quantity
Procedure of Volumetric Analysis:
- Take known volume of analyte in flask
- Add suitable indicator
- Fill burette with standard solution (titrant)
- Add titrant slowly until colour change
- Note volume at endpoint
- Calculate concentration using formula
Types of Volumetric Analysis:
- Acid–Base Titration: Based on neutralization reaction
- Non-Aqueous Titration: Used for weak or water-insoluble drugs
- Precipitation Titration: Formation of precipitate
- Complexometric Titration: Metal ion estimation using EDTA
- Redox Titration: Based on oxidation–reduction reactions
Acid–Base Titration:
Used to determine concentration of acids or bases based on neutralization reaction:
Acid + Base → Salt + Water
Indicators such as phenolphthalein are used to detect endpoint.
Non-Aqueous Titration:
Used for weak acids or bases that do not dissolve in water. Organic solvents like glacial acetic acid are used.
Indicators: Crystal violet, methyl red, thymol blue, quinaldine red.
Precipitation Titration:
Involves formation of a solid precipitate during reaction.
Methods: Mohr’s method, Volhard’s method, Fajan’s method.
Complexometric Titration:
Used for estimation of metal ions like Ca, Mg, Pb, and Zn using EDTA.
Indicators: Eriochrome Black T, Murexide, Xylenol Orange.
Redox Titration:
Based on oxidation and reduction reactions (electron transfer).
Examples include permanganate and iodine titrations.
Used for estimation of drugs such as aspirin, vitamin C, and antibiotics.
