Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Mercuric Sulfate (Mercury(II) Sulfate) 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 Sulfate 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, Residue after Reduction, Chloride, Nitrate, Iron, and Mercurous Mercury.
HgSO4
Formula Wt 296.65
CAS No. 7783-35-9
GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . white solid Applications . . . . . . . . . . . . . . . . . . . . . . . . determination of chemical oxygen demand; catalyst for Kjeldahl method Aqueous solubility . . . . . . . . . . . . . . . . . . . . decomposes into basic salt and sulfuric acid
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥98.0% HgSO4 Maximum Allowable Residue after reduction . . . . . . . . . . . . . . . . 0.02% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.003% Nitrate (NO3) . . . . . . . . . . . . . . . . . . . . . . . Passes test Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 0.005% Mercurous mercury (as Hg) . . . . . . . . . . . . . . 0.15%
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4218 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Assay (By thiocyanate precipitation titration of HgII). Weigh accurately about 0.5 g, and dissolve in 50 mL of dilute nitric acid (1:1). Add 1 mL of 10% ferric nitrate solution, and titrate with 0.1 N ammonium thiocyanate volumetric solution to a permanent reddish-brown color. One milliliter of 0.1 N ammonium thiocyanate corresponds to 0.01483 g of HgSO4.
Residue after Reduction Dissolve 5.0 g in 50 mL of water plus 10 mL of formic acid (96%), and add 25 mL of 30% ammonium hydroxide. Digest under total 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 0.1 mL of sulfuric acid to the combined filtrate and washings, and evaporate in a tared, preconditioned dish in a well-ventilated hood. Continue heating until the excess sulfuric acid has been volatilized. Finally, ignite at 800 ± 25 °C for 15 min. Correct for the weight obtained in a complete blank test. Retain the residue for the test for iron.
Chloride Dissolve 1.0 g in 50 mL of water plus 1 mL of formic acid (96%). Add dropwise 10% sodium hydroxide reagent solution until a small amount of permanent precipitate is formed. Digest under total reflux until all the mercury is reduced to metal and the solution is clear. Cool, filter through a chloride-free filter, and dilute to 90 mL. To 30 mL of this solution, add 1 mL of nitric acid and 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.
Nitrate Disperse 1.0 g in 9 mL of water, add 1 mL of sodium chloride solution (1 in 200), mix, and add 0.1 mL of indigo carmine reagent solution, followed by 10 mL of sulfuric acid. The blue color of the clear solution should not be discharged entirely within 5 min. (Limit about 0.003%.)
Iron [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. To the residue obtained in the test for residue after reduction, add 3 mL of dilute hydrochloric acid (1:1), cover with a watch glass, and digest on a hot plate (~100 °C) for 20 min. Remove the watch glass, and evaporate to dryness. Take up the residue in a mixture of 1 mL of dilute hydrochloric acid (1:1) and 30 mL of water, filter if necessary, and dilute with water to 100 mL. Use 4.0 mL of the solution.
Mercurous Mercury Transfer 5.0 g to a glass-stoppered flask. Add 100 mL of 15% potassium iodide solution, 5.00 mL of 0.1 N iodine, and 3 mL of 1 N hydrochloric acid. Allow to stand in the dark, with frequent agitation, for 1 h. Titrate the excess iodine with 0.1 N sodium thiosulfate volumetric solution, adding 3 mL of starch indicator solution near the end point. Correct for a blank determination. Not more than 0.38 mL of the 0.1 N iodine should be consumed.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4218 ACS Reagent Chemicals, Part 4
