Iodometry

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iodometry

[‚ī·ə′däm·ə·trē]
(analytical chemistry)
An application of iodine chemistry to oxidation-reduction titrations for the quantitative analysis in certain chemical compounds, in which iodine is used as a reductant and the iodine freed in the associated reaction is titrated, usually in neutral or slightly acid mediums with a standard solution of a reductant such as sodium thiosulfate or sodium arsenite; examples of chemicals analyzed are copper(III), gold(VI), arsenic(V), antimony(V), chlorine, and bromine.

Iodometry

 

a method used in the titrimetric analysis of substances exhibiting oxidizing or reducing properties based on the reversible reaction I2 + 2e ⇆ 2I. The I2/2I system, with a normal potential equal to +0.5345 V (25°C), is used for the determination of reducing agents with a potential lower than +0.5345 V (for example, stannous salts, hydrogen sulfide) and oxidizing agents with a potential greater than +0.5345 V (for example, peroxides, chromic and permanganic acids, cupric salts, and ferric salts). Solutions of iodine and sodium thiosulfate are used as standard solutions during titration, and starch serves as the indicator.

REFERENCE

Kreshkov, A. P. Osnovy analiticheskoi khimii, 3rd ed., part 2. Moscow, 1971.