Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Sodium Cyanide 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 Cyanide 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, Phosphate, Chloride, Sulfate, Sulfide, Thiocyanate, Iron, Total, and Lead.
NaCN
Formula Wt 49.01
CAS No. 143-33-9
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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white solid electroplating analysis; complexing agent melting point, 563 °C 58 g in 100 mL
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥95.0% NaCN
Phosphate (PO4) . . Chloride (Cl) . . . . Sulfate (SO4) . . . . Sulfide (S) . . . . . . Thiocyanate (SCN) . Iron, total (as Fe) . Lead (Pb) . . . . . .
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© 2017 American Chemical Society
Maximum Allowable 0.02% 0.15% 0.05% 0.005% 0.02% 0.005% 5 ppm
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DOI:10.1021/acsreagents.4343 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Assay (By argentimetric titration of cyanide content). Weigh accurately about 0.4 g, and dissolve in 30 mL of water. Add 0.20 mL of 10% potassium iodide reagent solution and 1 mL of ammonium hydroxide, and titrate with 0.1 N silver nitrate volumetric solution until a slight permanent yellowish turbidity forms. One milliliter of 0.1 N silver nitrate corresponds to 0.009802 g of NaCN.
Phosphate [Part 2: Colorimetry and Turbidimetry; Phosphate; Procedure for Phosphate, Method 1 (Direct Molybdenum Blue)]. Dissolve 1.0 g in 5 mL of water in a dish, add 2 mL of hydrochloric acid, and evaporate to dryness in a well-ventilated hood. Add 5 mL of dilute hydrochloric acid (1:1), and evaporate to dryness again. Dissolve the residue in 50 mL of approximately 0.5 N sulfuric acid. To 5.0 mL of the solution, add 20 mL of approximately 0.5 N sulfuric acid, and continue as described.
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For the Determination of Chloride, Sulfate, Sulfide, Thiocyanate, and Total Iron
S a m p l e S o l u t i o n A . Dissolve 10.0 g in water, filter if necessary through a chloride-free filter, and dilute with water to 200 mL (1 mL = 0.05 g).
Chloride† Dilute 1.0 mL of sample solution A (0.05 g sample) with water to 50 mL. To 10 mL of this solution in a beaker, add 5 mL of 30% hydrogen peroxide, and cover the beaker until the reaction ceases. Digest in the covered beaker on a hot plate (~100 °C) for about 30 min, cool, and neutralize with nitric acid. Dilute with water to 25 mL, and add 1 mL of nitric acid and 1 mL of silver nitrate reagent solution. The turbidity should not exceed that produced by 0.015 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 2]. Use 2 mL of sample solution A (0.1 g sample) plus 1 mL of hydrochloric acid in a well-ventilated hood.
Sulfide† To 10 mL of sample solution A (measured in a graduated cylinder) (0.5 g sample), add 10 mL of water and 0.15 mL of alkaline lead solution (made by adding 10% sodium hydroxide reagent solution to a 10% lead acetate reagent solution until the precipitate first formed is redissolved). The color should not be darker than that produced by 0.025 mg of sulfide ion (S) in an equal volume of solution when treated with 0.15 mL of the alkaline lead solution.
Thiocyanate† To 20 mL (measured in a graduated cylinder) of sample solution A (1 g sample), add 4 mL of hydrochloric acid and 0.20 mL of ferric chloride reagent solution. At the end of 5 min, the solution should show no reddish tint when compared with 20 mL of water to which have been added the quantities of hydrochloric acid and ferric chloride used in the test.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4343 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
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Iron, Total
[Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. Transfer 4.0 mL of sample solution A (0.2 g sample) to a platinum dish, add 3 mL of hydrochloric acid, and evaporate to dryness in a wellventilated hood. Heat the residue at 650 °C for 30 min, cool, and add 2 mL of hydrochloric acid and 10 mL of water. Cover with a watch glass, digest on a hot plate (~100 °C) until dissolution is complete, and use the solution without further acidification.
Lead Dissolve 0.50 g in 10 mL of water in a separatory funnel. Add 5 mL of ammonium citrate reagent solution (lead-free), 2 mL of hydroxylamine hydrochloride reagent solution for dithizone test, and 0.10 mL of phenol red indicator solution, and make the solution alkaline if necessary by adding ammonium hydroxide. Add 5 mL of dithizone extraction solution, shake gently but well for 1 min, and allow the layers to separate. The intensity of the red color of the chloroform layer should be no greater than that of a control made with 0.002 mg of lead ion (Pb) and 0.1 g of the sample dissolved in 10 mL of water and treated exactly like the solution of 0.50 g of sample in 10 mL of water.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4343 ACS Reagent Chemicals, Part 4
