Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Sodium Thiocyanate 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 Sodium Thiocyanate 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, Insoluble Matter, Carbonate, Chloride, Sulfate, Sulfide, Ammonium, Heavy Metals, and Iron.
NaSCN
Formula Wt 81.07
CAS No. 540-72-7
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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colorless or white solid titrimetry melting point, 300 °C soluble in 0.6 parts of water
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥98.0% NaSCN Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.005% Carbonate (as Na2CO3) . . . . . . . . . . . . . . . . . 0.2% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.01% Sulfate (SO4) . . . . . . . . . . . . . . . . . . . . . . . 0.01% Sulfide (S) . . . . . . . . . . . . . . . . . . . . . . . . . 0.001% Ammonium (NH4) . . . . . . . . . . . . . . . . . . . . 0.002% Heavy metals (as Pb) . . . . . . . . . . . . . . . . . . 5 ppm Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 2 ppm
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4374 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Assay (By indirect argentimetric titration). Weigh, to the nearest 0.1 mg, about 6.0 g of sample, dissolve with 100 mL of water in a 1000 mL volumetric flask, dilute to volume with water, and mix well. To 50.0 mL in a 250 mL glass-stoppered flask, add while agitating exactly 50.0 mL of 0.1 N silver nitrate volumetric solution, then add 3 mL of nitric acid and 2 mL of ferric ammonium sulfate indicator solution, and titrate the excess silver nitrate with 0.1 N ammonium thiocyanate volumetric solution. One milliliter of 0.1 N silver nitrate corresponds to 0.008107 g of NaSCN.
Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Use 20.0 g dissolved in 150 mL of water.
Carbonate Dissolve 10.0 g in 100 mL of carbon dioxide-free water, add 0.10 mL of methyl orange indicator solution, and titrate with 0.1 N sulfuric acid. Not more than 3.8 mL of the acid should be required.
Chloride Dissolve 0.50 g in 20 mL of water, filter if necessary through a chloride-free filter, and add 10 mL of 25% sulfuric acid reagent solution and 7 mL of 30% hydrogen peroxide. Evaporate to 20 mL by boiling in a well-ventilated hood, add 15–20 mL of water, and evaporate again. Repeat until all of the cyanide has been volatilized, cool, and dilute with water to 100 mL. To 20 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.
Sulfate [Part 2: Colorimetry and Turbidimetry; Sulfate; Procedure for Sulfate, Method 1].
Sulfide Add 5.0 g to 80 mL of solution prepared by mixing 10 mL of ammonium hydroxide and 10 mL of silver nitrate reagent solution in 60 mL of water. Heat on a hot plate (~100 °C) with occasional shaking for 20 min, and transfer to a color comparison tube. Any color should not exceed that produced by 0.05 mg of sulfide ion (S) in an equal volume of solution containing the quantities of reagents used in the test.
Ammonium (By colorimetry, [Part 2: Colorimetry and Turbidimetry; Ammonium (Test for Ammonia and Amines)]). Dilute the distillate from a 1.0 g sample to 100 mL, and use 50 mL of the dilution. For the standard, use 0.01 mg of ammonium ion (NH4).
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4374 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Heavy Metals [Part 2: Colorimetry and Turbidimetry; Heavy Metals (as Lead); Procedure for Heavy Metals, Method 1]. Dissolve 6.0 g in about 20 mL of water, and dilute with water to 30 mL. Use 25 mL to prepare the sample solution, and use the remaining 5.0 mL to prepare the control solution.
Iron Dissolve 10.0 g in 60 mL of water. To 30 mL of the solution, add 0.1 mL of hydrochloric acid, 6 mL of hydroxylamine hydrochloride reagent solution, and 4 mL of 1,10-phenanthroline reagent solution, and then add ammonium hydroxide to bring the pH to approximately 5. Any red color should not exceed that produced by 0.01 mg of iron in an equal volume of solution containing the quantities of reagents used in the test. Compare 1 h after adding the reagents to the sample and standard solutions.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4374 ACS Reagent Chemicals, Part 4
