Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Hydrobromic Acid, 48% 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 Hydrobromic Acid, 48% provides, in addition to common physical constants, a general description including typical appearance, applications, aqueous solubility, density, and pKa. The monograph also details the following specifications and corresponding tests for verifying that a substance meets ACS Reagent Grade specifications including: Assay, Residue after Ignition, Chloride, Iodide, Phosphate, Sulfate, Sulfite, Heavy Metals, Iron, and Selenium.
HBr
Formula Wt 80.91
CAS No. 10035-10-6
GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . clear liquid, colorless to pale yellow when fresh; may become yellow to brown on storage Applications . . . . . . . . . . . . . . . . . . . . . . . . catalyst Aqueous solubility . . . . . . . . . . . . . . . . . . . . miscible Density . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 pKa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –9
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47.0–49.0% HBr Maximum Allowable Residue after ignition. . . . . . . . . . . . . . . . . . 0.002% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.05% Iodide (I). . . . . . . . . . . . . . . . . . . . . . . . . . 0.003% Phosphate (PO4) . . . . . . . . . . . . . . . . . . . . . 0.001% Sulfate and sulfite (as SO4) . . . . . . . . . . . . . . 0.003% Heavy metals (by ICP–OES) . . . . . . . . . . . . . . 5 ppm Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 1 ppm Selenium (Se) . . . . . . . . . . . . . . . . . . . . . . . 0.01 ppm
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4162 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Assay (By acid–base titrimetry). Tare a glass-stoppered conical flask containing about 15 mL of water. Quickly add about 4 mL of the acid, and weigh. Dilute with water to 50 mL, and titrate with 1 N sodium hydroxide volumetric solution, using 0.15 mL of phenolphthalein indicator solution. One milliliter of 1 N sodium hydroxide corresponds to 0.08091 g of HBr.
Residue after Ignition [Part 2: Gravimetric Methods; Residue after Ignition]. To 50 g (34 mL) in a tared, preconditioned dish (not platinum), add 0.05 mL of sulfuric acid, evaporate as far as possible on a hot plate (~100 °C), then heat gently to volatilize the solution. Finally, ignite at 600 ± 25 °C for 15 min.
Chloride To 1 g (0.67 mL) in a 150 mL conical flask, add 50 mL of dilute nitric acid (1:3), and digest on a hot plate (~100 °C) until the solution is colorless. Wash down the sides of the flask with a little water, and digest for an additional 15 min. Cool, filter if necessary through a chloride-free filter, and dilute with water to 100 mL. Dilute 2.0 mL of the solution with water to 23 mL. Prepare a standard containing 0.01 mg of chloride ion (Cl) in 23 mL of water. Add 1 mL of nitric acid and 1 mL of silver nitrate reagent solution to each. Any turbidity produced in the solution of the sample should not exceed that in the standard.
Iodide Dilute 6 g (4.0 mL) with 20 mL of water. Add 5 mL of chloroform, 0.2 mL of 10% ferric chloride solution, and 0.1 mL of dilute sulfuric acid (1:15), and mix gently in a separatory funnel. Draw off the chloroform layer into a comparison tube of about 1.5 cm diameter. No violet color should be observed on looking down through the chloroform.
Phosphate [Part 2: Colorimetry and Turbidimetry; Phosphate; Procedure for Phosphate, Method 1 (Direct Molybdenum Blue)]. Add 5 mL of nitric acid to 6 g (4.0 mL) of the sample, and evaporate to dryness on a hot plate (~100 °C). Dissolve the residue in 75 mL of approximately 0.5 N sulfuric acid, and use 25 mL of the solution.
Sulfate and Sulfite Dilute 2.7 mL (4.0 g) of the sample with water to 20 mL. Add 0.5 mL of bromine water, and gently heat to boil for a few minutes to expel excess bromine. Add 1.0 mL of 1% sodium carbonate reagent solution, and evaporate to dryness on a hot plate (~100 °C). Dissolve the residue in 1 mL of (1:19) hydrochloric acid and 20 mL of water. Filter through small, washed filter paper, add two 3 mL portions of water through, and dilute to 35 mL with water. For the control, take 0.12 mg of sulfate ion (SO4) in 30 mL of water, add 1 mL of (1:19) hydrochloric acid, dilute to 35 mL with water, add 1 mL of 12% barium chloride reagent solution, and compare turbidity after 10 min. Sample turbidity should not exceed that of control solution.
Heavy Metals ([Part 2: Trace and Ultratrace Elemental Analysis; Inductively Coupled Plasma−Optical Emission Spectroscopy (ICP–OES); Calculation of Heavy Metals (by ICP–OES) Results], by ICP–OES). Use 2.0 g sample.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4162 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Iron [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. To 10 g (6.6 mL), add about 10 mg of sodium carbonate, and evaporate to dryness on a hot plate (~100 °C). Dissolve the residue in 2 mL of hydrochloric acid, dilute with water to 50 mL, and use the solution without further acidification.
Selenium Place 150 g (100 mL) in an all-glass distilling apparatus, add 2 mL of bromine, and distill off approximately 25 mL. Dilute the distillate with an equal volume of water, and decolorize with sulfurous acid. Add 0.1 g of hydroxylamine hydrochloride, and warm gently on a hot plate (~100 °C) for 30 min. Cool to room temperature, filter through a white glass-wool mat in a small Gooch crucible, without washing, and examine immediately. No pink or red color should be observed on the mat.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4162 ACS Reagent Chemicals, Part 4
