Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Osmium Tetroxide (Osmic Acid) 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 Osmium Tetroxide 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: Clarity of Solution, Assay, Identification. Special caution is advised for the handling or testing of this substance.
OsO4
Formula Wt 254.23
CAS No. 20816-12-0
C a u t i o n : Osmium tetroxide vapors are poisonous and highly irritating to the eyes and respiratory membranes. Use only in a well-ventilated fume hood.
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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pale yellow solid catalyst in redox titrations melting point, 41 °C 7.24 g in 100 g at 25 °C
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥98.0% OsO4 Clarity of solution . . . . . . . . . . . . . . . . . . . . Passes test Identification . . . . . . . . . . . . . . . . . . . . . . . Passes test
© 2017 American Chemical Society
A
DOI:10.1021/acsreagents.4250 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Clarity of Solution Accurately weigh about 0.20 g, and add to 5 mL of reagent alcohol. The resulting solution is clear and not more than slightly yellow, and no appreciable amount of insoluble residue remains. Reserve the solution for the assay test.
Assay and Identification (Assay by iodometry). To the solution from the clarity of solution test, add 5–7 mL of 1 N sodium hydroxide volumetric solution in a glass-stoppered flask. A dark red precipitate is produced (identification). Add 3 g of potassium iodide, mix to dissolve, slowly add 40 mL of 25% sulfuric acid, stopper, and let stand in a dark place for 20 min. Titrate the liberated iodine with 0.1 N sodium thiosulfate volumetric solution, using starch indicator solution as an external indicator (the reduced osmium solution is green, and the end point may be difficult to determine with an internal indicator). Correct for a blank. One milliliter of 0.1 N sodium thiosulfate corresponds to 0.006355 g of OsO4.
© 2017 American Chemical Society
B
DOI:10.1021/acsreagents.4250 ACS Reagent Chemicals, Part 4
