Study Set Content:
Standardization of 0.1N Sodium Thiosulfate
Assay
Iodometry
Standardization of 0.1N Iodine solution
primary standard
Arsenic trioxide (As2O3), mEq:
198g/mol/4000 = 0.0495
Standardization of 0.1N Iodine solution
Titrant
Iodine
Standardization of 0.1N Iodine solution
Indicator
Starch TS
Standardization of 0.1N Iodine solution
Visual End point
Deep blue/ Violet
Standardization of 0.1N Iodine solution
Assay
Iodimetric
Preparation of Starch TS
Triturate 1g of arrowroot starch with 10ml of cold water. Triturate until a pasty consistency occurs. Boil 200ml of hot water and add to the starch paste. Boil the solution for 30 mins or until a thin translucent solution is formed.
Since a solution of starch deteriorates rapidly, it should be prepared freshly
each day
Upon heating, starch granules burst and form colloidal dispersion, composed of
beta amylose
Interaction of Iodine and iodide ion to beta-amylose results in the formation of a distinct
blue color
Assay of Hydrogen Peroxide Solution
Primary Standard
H2O2, mEq: 0.017
Assay of Hydrogen Peroxide Solution
Titrant
KMnO4
Assay of Hydrogen Peroxide Solution
Indicator
None
Assay of Hydrogen Peroxide Solution
Visual Endpoint
Pale pink color
Assay of Hydrogen Peroxide Solution
Assay
Direct Permanganometry
Hydrogen peroxide concentrations are expressed as volumes:
3%H2O2 is expressed as 10 volumes
Assay of Ascorbic Acid
Analyte
Ascorbic Acid (C6H8O6),
mEq: 0.088
Assay of Ascorbic Acid
Titrant
Iodine
Assay of Ascorbic Acid
Indicator
Starch TS
Assay of Ascorbic Acid
Visual Endpoint
Deep blue/Violet
