Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Ammonium Peroxydisulfate (Ammonium 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 Ammonium 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, Residue after Ignition, Titrable Free Acid, Chloride, Chlorate, Heavy Metals, Iron, and Manganese.
(NH4)2S2O8
Formula Wt 228.19
CAS No. 7727-54-0
Note: Because of its inherent instability, this reagent may be expected to decrease in strength and to increase in acidity during storage. After storage for some time, the reagent may fail to meet the specified requirements for assay and acidity. Store in a dry, cool place.
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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white or colorless solid detection and determination of manganese and iron melting point, 120 °C with decomposition 58 g in 100 mL at 20 °C
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥98.0% (NH4)2S2O8
Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.005% Residue after ignition. . . . . . . . . . . . . . . . . . 0.05%
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4031 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Titrable free acid . . . . . . . Chloride and chlorate (as Cl) Heavy metals (as Pb) . . . . . Iron (Fe) . . . . . . . . . . . . . Manganese (Mn) . . . . . . . .
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0.04 meq/g 0.001% 0.005% 0.001% 0.5 ppm
TESTS Assay (By oxidation–reduction titration of persulfate). Weigh accurately about 0.4 g and add it to 50.0 mL of 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, and titrate the excess ferrous ammonium sulfate with 0.1 N potassium permanganate volumetric solution. Run a complete blank. One milliliter of 0.1 N ferrous ammonium sulfate corresponds to 0.01141 g of (NH4)2S2O8.
Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Use 20 g dissolved in 200 mL of water.
Residue after Ignition [Part 2: Gravimetric Methods; Residue after Ignition]. Ignite 5.0 g.
Titrable Free Acid Dissolve 10.0 g in 100 mL of water, and add 0.01 mL of methyl red indicator solution. If a red color is produced, not more than 4.0 mL of 0.1 N sodium hydroxide should be required to discharge it.
Chloride and Chlorate [Part 2: Colorimetry and Turbidimetry; Chloride]. Mix 1.0 g with 1 g of sodium carbonate, and heat until no more gas is evolved. Dissolve the residue in 20 mL of water, and neutralize with nitric acid.
Heavy Metals [Part 2: Colorimetry and Turbidimetry; Heavy Metals (as Lead); Procedure for Heavy Metals, Method 1]. Gently ignite 2.0 g in a porcelain or silica crucible or dish (not in platinum), and to the residue add 1 mL of hydrochloric acid, 1 mL of nitric acid, and about 10 mg of sodium carbonate. Evaporate to dryness on a hot plate (~100 °C), dissolve the residue in about 20 mL of water, and dilute with water to 50 mL. Dilute 10 mL of the solution with water to 25 mL.
Iron [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. To 1.0 g, add 5 mL of water and 10 mL of hydrochloric acid, and evaporate to dryness. Dissolve the residue in 2 mL of hydrochloric acid, dilute with water to 50 mL, and use this solution without further acidification. Prepare the standard solution from the residue remaining from evaporation of 10 mL of hydrochloric acid.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4031 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Manganese Gently ignite 20.0 g in a dish (but not in platinum) until the sample is decomposed, and finally ignite at 600 °C until the sample is volatilized. Dissolve the residue by boiling for 5 min with 35 mL of water plus 10 mL of nitric acid, 5 mL of sulfuric acid, and 5 mL of phosphoric acid, and cool. Prepare a standard containing 0.01 mg of manganese ion (Mn) in an equal volume of solution containing the quantities of reagents used to dissolve the residue. To each solution add 0.25 g of potassium periodate, boil gently for 5 min, and cool. Any pink 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.4031 ACS Reagent Chemicals, Part 4
