Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Mercuric Iodide, Red (Mercury(II) Iodide, Red) 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 Mercuric Iodide, Red 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, Solubility in Potassium Iodide Solution, Mercurous Mercury, and Soluble Mercury Salts.
HgI2
Formula Wt 454.40
CAS No. 7774-29-0
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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red solid preparation of Nessler’s reagent melting point, 259 °C insoluble
SPECIFICATIONS Assay (dried basis). . . . . . . . . . . . . . . . . . . . ≥99.0% HgI2 Solubility in potassium iodide solution . . . . . . . Passes test Maximum Allowable Mercurous mercury (as Hg) . . . . . . . . . . . . . . 0.1% Soluble mercury salts (as Hg) . . . . . . . . . . . . . 0.05%
© 2017 American Chemical Society
A
DOI:10.1021/acsreagents.4214 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Assay (By iodometry). Dry about 1 g of sample over magnesium perchlorate for at least 8 h. Weigh accurately about 0.5 g of the dried sample, place in a glass-stoppered conical flask, and add 30 mL of hydrochloric acid and 20 mL of water. Rotate the flask until the mercuric iodide is dissolved, add 5 mL of chloroform, and titrate the solution with 0.05 M potassium iodate volumetric solution until the iodine color is discharged from the aqueous layer. Stopper the flask, stir well for 30 s, then continue the titration, stirring vigorously after each addition of the potassium iodate until the chloroform is free of iodine color. One milliliter of 0.05 M potassium iodate corresponds to 0.02272 g of HgI2.
Solubility in Potassium Iodide Solution Dissolve 10.0 g of the sample in 100 mL of 10% potassium iodide reagent solution in a glass-stoppered flask. A complete, or practically complete, solution results. Retain the solution for the test for mercurous mercury.
Mercurous Mercury To the solution reserved from the test for solubility in potassium iodide solution, add 5.0 mL of 0.1 N iodine and 3 mL of 1 N hydrochloric acid. Allow to stand in a dark place for 1 h with frequent agitation. Titrate the excess iodine with 0.1 N sodium thiosulfate volumetric solution, adding 3 mL of starch indicator solution near the end point, and correct for a complete blank. Not more than 0.50 mL of the 0.1 N iodine should be consumed.
Soluble Mercury Salts Shake 1.0 g of the sample with 20 mL of water for 2 min, and filter. Dilute 10 mL of the filtrate with water to 40 mL, and add 10 mL of freshly prepared hydrogen sulfide water. Any color should not exceed that produced by 0.25 mg of mercury ion (Hg) in an equal volume of solution containing the quantities of reagents used in the test.
© 2017 American Chemical Society
B
DOI:10.1021/acsreagents.4214 ACS Reagent Chemicals, Part 4
