Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Potassium Permanganate 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 Permanganate provides, in addition to common physical constants, a general description including typical appearance, applications, 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, Chloride, Chlorate, and Sulfate.
KMnO4
Formula Wt 158.03
CAS No. 7722-64-7
GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . dark solid Applications . . . . . . . . . . . . . . . . . . . . . . . . oxidizing agent Aqueous solubility . . . . . . . . . . . . . . . . . . . . 6.4 g in 100 mL at 20 °C
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥99.0% KMnO4 Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.2% Chloride and chlorate (as Cl) . . . . . . . . . . . . . 0.005% Sulfate (SO4) . . . . . . . . . . . . . . . . . . . . . . . 0.02%
TESTS Assay (By titration of oxidizing power). Weigh, to the nearest 0.1 mg, about 1.5 g of sample. Transfer to a 500 mL volumetric flask, dissolve with water, then dilute to the mark with water, and mix thoroughly. Weigh accurately about 0.25 g of NIST SRM or primary standard sodium oxalate (dried at 105 °C), and dissolve in a 500 mL glass-stoppered flask. Add 15 mL of 25% sulfuric acid reagent solution, and then add from a burette 30 mL of 0.1 N potassium permanganate volumetric solution. Heat the
© 2017 American Chemical Society
A
DOI:10.1021/acsreagents.4301 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
solutions to about 70 °C, and complete the titration with 0.1 N potassium permanganate. One milliliter of 0.1 N potassium permanganate corresponds to 0.02358 g of KMnO4.
Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Dissolve 2.0 g in 150 mL of warm water on a hot plate (~100 °C). Filter at once through a tared filtering crucible, wash thoroughly, and dry at 105 °C.
Chloride and Chlorate Dissolve 1.0 g in 75 mL of water, and add 5 mL of nitric acid and 3 mL of 30% hydrogen peroxide. After reduction is complete, filter if necessary through a chloride-free filter, and dilute with water to 100 mL. To 20 mL of this solution, add 1 mL of silver nitrate reagent solution. Any turbidity should not exceed that produced by 0.01 mg of chloride ion (Cl) in an equal volume of solution containing the quantities of reagents used in the test.
Sulfate Dissolve 5.0 g in 75 mL of water, and add 10 mL of reagent alcohol [Part 4: Reagent Alcohol] and 10 mL of hydrochloric acid. Heat until colorless, adding more alcohol and a little hydrochloric acid if necessary. Evaporate to dryness. Dissolve the residue in 100 mL of dilute hydrochloric acid (1:99), filter, and heat to boiling. Add 5 mL of 12% barium chloride reagent solution, digest in a covered beaker on a hot plate (~100 °C) for 2 h, and allow to stand for at least 8 h. Filter, wash thoroughly, and ignite. The weight of the precipitate should not be more than 0.0024 g greater than the weight obtained in a complete blank test.
© 2017 American Chemical Society
B
DOI:10.1021/acsreagents.4301 ACS Reagent Chemicals, Part 4
