Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Mercurous Chloride (Mercury(I) Chloride) 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 Mercurous Chloride 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, Residue after Reduction, Mercuric Chloride, and Sulfate.
Hg2Cl2
Formula Wt 472.08
CAS No. 10112-91-1
GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . white solid Applications . . . . . . . . . . . . . . . . . . . . . . . . preparation of standard electrodes Change in state (approximate) . . . . . . . . . . . . slowly decomposes by sunlight into mercuric chloride and metallic mercury; sublimes at 400–500 °C without melting Aqueous solubility . . . . . . . . . . . . . . . . . . . . practically insoluble
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥99.5% Hg2Cl2 Maximum Allowable Residue after reduction . . . . . . . . . . . . . . . . 0.02% Mercuric chloride (HgCl2) . . . . . . . . . . . . . . . 0.01% Sulfate (SO4) . . . . . . . . . . . . . . . . . . . . . . . 0.01%
© 2017 American Chemical Society
A
DOI:10.1021/acsreagents.4219 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Assay (By iodometric titration of mercury). Weigh accurately about 0.9 g, and transfer to a 250 mL glass-stoppered conical flask. Add 50.0 mL of 0.1 N iodine and 2 g of potassium iodide. Stopper, and swirl until the precipitate redissolves. Titrate the excess of iodine with 0.1 N sodium thiosulfate volumetric solution, adding 3 mL of starch indicator solution near the end point. One milliliter of 0.1 N iodine corresponds to 0.02360 g of Hg2Cl2.
Residue after Reduction Dissolve 5.0 g in 10 mL of water plus 10 mL of ammonium hydroxide. Add 40 mL of formic acid (96%), and reflux until all the mercury is reduced to metal. Cool, filter through a thoroughly washed filter paper, and wash with a small quantity of water. Add 0.10 mL of sulfuric acid to the combined filtrate and washings. Evaporate in a tared, preconditioned dish in a wellventilated hood. Continue heating until the excess sulfuric acid has been volatilized. Ignite at 800 ± 25 °C for 15 min. Correct for the weight obtained in a complete blank test.
Mercuric Chloride Shake 1.0 g with 10 mL of ethyl alcohol for 5 min, and filter. To 5 mL of the filtrate, add 0.10 mL of hydrochloric acid and 5 mL of freshly prepared hydrogen sulfide water. Any darkening should not be more than that produced by 0.05 mg of mercuric chloride (HgCl2) in a mixture of 5 mL of alcohol, 0.10 mL of hydrochloric acid, and 5 mL of hydrogen sulfide water.
Sulfate [Part 2: Colorimetry and Turbidimetry; Sulfate; Procedure for Sulfate, Method 3]. Digest for 10 min with 10 mL of dilute hydrochloric acid (1:1), and filter.
© 2017 American Chemical Society
B
DOI:10.1021/acsreagents.4219 ACS Reagent Chemicals, Part 4
