Study Set Content:
Sample Assays
FeSO4 tablets (direct, using orthophenanthroline as indicator); Menadione (indirect)
direct procedure
- The reversible reaction 2I ↔ I2 + 2e can be applied in analysis of reducing agents such as thiosulfates and arsenites by the use of standard solutions of iodine.
Iodimetry
the sample of oxidizing agent is reduced with excess potassium iodide and an equivalent amount of iodine is produced.
- Iodine formed is titrated with a standard solution of sodium thiosulfate.
Iodimetry
indirect procedure
Both methods use what as an indicator
Starch TS
Both methods use Starch TS as indicator but differs to when this will be added: at the start for Iodimetry
(colorless to deep blue/ violet
and before the endpoint for Iodometry (
discharge of deep blue/ violet color)
Sample Assays:
Iodimetry
Direct: Ascorbic Acid, Tartar Emetic – using 0.1N I2 VS Iodine, Strong iodine solution – using 0.1N As2O3 Residual: NaHSO3, Na2SO3, calomel, antipyrine
Sample Assays:
Iodimetry
Iodometry
Direct: Cupric sulfate, Ferric sulfate, NaOCl solution Residual: Phenol, Resorcinol
Miscellaneous Redox:
Diazotization Method
Titrant:
0.1N NaNO2 VS
Analyte:
1˚ aromatic amines – Sulfa drugs; Benzocaine, Procaine, Tetracaine; Dapsone
Nature:
Direct titration
is a technique through which the amount of an analyte (the ion being analyzed) can be determined through the measurement of mass.
Gravimetric analysis
- depend on comparing the masses of two compounds containing the analyte.
Gravimetric analysis
physical separation
Physical Gravimetry
samples are heated
Thermogravimetry
chemical precipitation of an analyte
Precipitative gravimetric analysis
electrochemical reduction of metal ions
Electrodeposition
The Use of Gravimetric method for the following reasons:
1. The ion being analyzed must be completely precipitated.
2. The precipitate must be a pure compound.
3. The precipitate must be easily filtered.
2a.1 Based on absorption of radiant energy
2. Instrumental Method
2a. Optical method
