Principles and applications of Cerimetry

Cerimetry is a type of redox titration that involves the use of cerium(IV) as the oxidizing agent. It is based on the principle that cerium(IV) ions can be reduced to cerium(III) ions by a variety of reducing agents, including iodides, thiosulfates, and oxalic acid. The endpoint of the titration is determined by the disappearance of the yellow color of the cerium(IV) ion, which is due to its reduction to the colorless cerium(III) ion.

The basic principle of cerimetry is similar to other redox titration methods, in which the equivalence point is reached when the number of electrons lost by the oxidizing agent is equal to the number of electrons gained by the reducing agent. The concentration of the reducing agent can be calculated from the volume and concentration of the cerium(IV) solution used in the titration.

Cerimetry has a wide range of applications in analytical chemistry, including:

1. Determination of iodine: Cerimetry can be used for the determination of iodine in a variety of samples, including pharmaceuticals, food products, and environmental samples. Iodide ions react with cerium(IV) ions to form iodine, which is then titrated with a standard solution of sodium thiosulfate.
2. Determination of sulfite: Cerimetry can also be used for the determination of sulfite, which is commonly used as a preservative in food products. Sulfite reacts with cerium(IV) ions to form cerium(III) ions, which is then titrated with a standard solution of iodine.
3. Determination of oxalic acid: Cerimetry can be used for the determination of oxalic acid, which is commonly used as a reductant in a variety of chemical reactions. Oxalic acid reacts with cerium(IV) ions to form cerium(III) ions, which is then titrated with a standard solution of potassium permanganate.
4. Determination of iron: Cerimetry can also be used for the determination of iron in a variety of samples, including ores, soils, and water samples. Iron reacts with cerium(IV) ions to form cerium(III) ions, which is then titrated with a standard solution of potassium permanganate.

Overall, cerimetry is a versatile and widely used analytical method in the determination of various analytes, particularly those that can be reduced by cerium(IV) ions.

First Year B Pharm Notes, Syllabus, Books, PDF Subjectwise/Topicwise

Suggested readings:

• Metal ion indicators in Complexometric titration
• 407P Physical Pharmaceutics II Practical
• Volhard’s method in Precipitation titrations
• 306P Physical Pharmaceutics I Practical
• Classification of Complexometric titration