Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Potassium Peroxydisulfate (Potassium Persulfate) Part 4, Monographs for Reagent Chemicals: General Descriptions, Specifications, and Tests eISBN: 9780841230460 Tom Tyner Chair, ACS Committee on Analytical Reagents James Francis Secretary, ACS Committee on Analytical Reagents
ABSTRACT This monograph for Potassium Peroxydisulfate provides, in addition to common physical constants, a general description including typical appearance, applications, change in state (approximate), and aqueous solubility. The monograph also details the following specifications and corresponding tests for verifying that a substance meets ACS Reagent Grade specifications including: Assay, Insoluble Matter, Chlorine Compounds, Heavy Metals, Iron, and Manganese.
K2S2O8
Formula Wt 270.32
CAS No. 7727-21-1
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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colorless or white solid oxidizing agent decomposed by heat or humidity 5 g in 100 mL at 20 °C
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥99.0% K2S2O8 Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.005% Chlorine compounds (as Cl) . . . . . . . . . . . . . . 0.001% Heavy metals (as Pb) . . . . . . . . . . . . . . . . . . 0.001% Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 5 ppm Manganese (Mn) . . . . . . . . . . . . . . . . . . . . . 2 ppm
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4303 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Assay (By titration of oxidizing power). Weigh accurately about 0.5 g, and add it to 50.0 mL of freshly prepared 0.1 N ferrous ammonium sulfate volumetric solution in a glass-stoppered flask. Stopper the flask, allow it to stand for 1 h with frequent shaking, add 5 mL of phosphoric acid, and titrate the excess ferrous ammonium sulfate with 0.1 N potassium permanganate volumetric solution. Add 5 mL of phosphoric acid to 50.0 mL of ferrous ammonium sulfate volumetric solution, and titrate with 0.1 N potassium permanganate volumetric solution. The difference in the volume of permanganate consumed in the two titrations is equivalent to the potassium peroxydisulfate. One milliliter of 0.1 N potassium permanganate corresponds to 0.01352 g of K2S2O8.
Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Use 20 g dissolved in 200 mL of water.
Chlorine Compounds Mix 1.0 g with 1 g of anhydrous sodium carbonate, and fuse in a porcelain dish in a muffle furnace. Cool, dissolve the residue in 20 mL of water, neutralize with nitric acid, and add an excess of 1 mL of the acid. Filter if necessary through a chloridefree filter, and add 1 mL of silver nitrate reagent solution. Any turbidity should not exceed that in a standard containing 0.01 mg of chloride ion (Cl) and 1 g of sodium carbonate fused and acidified as in the test.
Heavy Metals [Part 2: Colorimetry and Turbidimetry; Heavy Metals (as Lead); Procedure for Heavy Metals, Method 1]. Dissolve 2.0 g in 20 mL of hot water, add 5 mL of hydrochloric acid, and evaporate to about 5 mL. Cool, and dilute with water to 25 mL. For the standard, use 0.02 mg of lead in 5 mL of hydrochloric acid, add 10 mL of water and 0.25 mL of sulfuric acid, evaporate to fumes of sulfur trioxide, cool, and dilute with water to 25 mL.
Iron [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. To 2.0 g, add 20 mL of hot water and 5 mL of hydrochloric acid, and evaporate to dryness. Moisten the residue with 2 mL of hydrochloric acid, dilute with water to 50 mL, and use the solution without further acidification.
Manganese To 5.0 g in a 150 mL beaker, add 5 mL of sulfuric acid and 5 mL of phosphoric acid. Heat to dissolve the sample, and continue heating to fumes of sulfur trioxide. Cool, dilute with water to 45 mL, add 10 mL of nitric acid, and boil for 5 min. Cool, add about 0.25 g of potassium periodate, and boil for 5 min. Cool, and compare with a standard prepared by treating 0.01 mg of manganese ion (Mn) in the same manner, using the same quantities of reagents (with no sample), except that the standard solution need not be fumed before adding the nitric acid. Any color in the solution of the sample should not exceed that in the standard.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4303 ACS Reagent Chemicals, Part 4
