Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Sodium Bromide 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 Bromide 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, pH of a 5% Solution at 25.0 °C, Insoluble Matter, Bromate, Chloride, Sulfate, Barium, Heavy Metals, Iron, Calcium, Magnesium, and Potassium.
NaBr
Formula Wt 102.89
CAS No. 7647-15-6
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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white or colorless solid standard in ion chromatography melting point, 755 °C 90 g in 100 mL at 20 °C
SPECIFICATIONS Assay (corrected) . . . . . . . . . . . . . . . . . . . . ≥99.0% NaBr pH of a 5% solution at 25.0 °C . . . . . . . . . . . . 5.0–8.8
Insoluble matter . . . Bromate (BrO3) . . . . Chloride (Cl) . . . . . Sulfate (SO4) . . . . . Barium (Ba) . . . . . . Heavy metals (as Pb) Iron (Fe) . . . . . . . .
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© 2017 American Chemical Society
Maximum Allowable 0.005% 0.001% 0.2% 0.002% 0.002% 5 ppm 5 ppm
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DOI:10.1021/acsreagents.4335 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Calcium (Ca) . . . . . . . . . . . . . . . . . . . . . . . 0.002% Magnesium (Mg) . . . . . . . . . . . . . . . . . . . . . 0.001% Potassium (K) . . . . . . . . . . . . . . . . . . . . . . . 0.1%
TESTS Assay (By argentimetric titration of bromide content). Weigh, to the nearest 0.1 mg, about 0.4 g of sample. Transfer to a 250 mL titration flask, and dissolve in 25 mL of water. Add slowly, while agitating, 50.0 mL of 0.1 N silver nitrate volumetric solution, then add 3 mL of nitric acid and 10 mL of benzyl alcohol, and shake vigorously. Add 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 0.01029 g of NaBr (uncorrected).
pH of a 5% Solution at 25.0 °C [Part 2: Direct Electrometric Methods; pH Potentiometry; pH Range; Procedure for pH of a 5% Solution at 25.0 °C].
Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Use 20 g dissolved in 150 mL of water.
Bromate [Part 2: Direct Electrometric Methods; Specific Polarographic Procedures; Polarographic Procedure for Bromate and Iodate]. Use 10.0 g of sample in 25 mL of solution. For the standard, add 0.10 mg of bromate ion (BrO3).
Chloride Dissolve 0.50 g in 15 mL of dilute nitric acid (1:2) in a small flask. Add 3 mL of 30% hydrogen peroxide, and digest on a hot plate (~100 °C) until the solution is colorless. Wash down the sides of the flask with a little water, digest for an additional 15 min, cool, and dilute with water to 200 mL. Dilute 2.0 mL with water to 20 mL, and 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].
Barium For the sample, dissolve 6.0 g in 15 mL of water. For the control, dissolve 1.0 g in 15 mL of water, and add 0.1 mg of barium ion (Ba). To each solution, add 5 mL of acetic acid, 5 mL of 30% hydrogen peroxide, and 1 mL of hydrochloric acid. Digest in
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4335 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
a covered beaker on a hot plate (~100 °C) until reaction ceases, uncover, and evaporate to dryness. Dissolve the residues in 15 mL of water, filter if necessary, and dilute with water to 23 mL. Add 2 mL of 10% potassium dichromate reagent solution, and add ammonium hydroxide until the orange color is just dissipated and the yellow color persists. Add 25 mL of methanol, stir vigorously, and allow to stand for 10 min. Any turbidity in the solution of the sample should not exceed that in the control.
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 50 mL. Use 25 mL to prepare the sample solution, and use the remaining 5.0 mL to prepare the control solution..
Iron Dissolve 2.0 g in 40 mL of water plus 2 mL of hydrochloric acid, and dilute with water to 50 mL. Add 30–50 mg of ammonium peroxydisulfate crystals and 3 mL of 30% ammonium thiocyanate reagent solution. Any red color should not exceed that produced by 0.01 mg of iron ion (Fe) in an equal volume of solution containing the quantities of reagents used in the test.
Calcium, Magnesium, and Potassium (By flame AAS, [Part 2: Trace and Ultratrace Elemental Analysis; Atomic Absorption Spectroscopy; Analysis; Procedure for Flame AAS]).
For the Determination of Calcium, Magnesium, and Potassium
S a m p l e S t o c k S o l u t i o n . Dissolve 5.0 g of sample with water in a 100 mL volumetric flask, and dilute to the mark with water (1 mL = 0.05 g).
For the Determination of Calcium, Magnesium, and Potassium
Element
Wavelength (nm)
Sample Wt (g)
Standard Added (mg)
Flame Type*
Background Correction
Ca
422.7
1.0
0.02; 0.04
N/A
No
Mg
285.2
1.0
0.01; 0.02
A/A
Yes
K
766.5
0.05
0.025; 0.05
A/A
No
*A/A is air/acetylene; N/A is nitrous oxide/acetylene.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4335 ACS Reagent Chemicals, Part 4
