Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Nitric Acid 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 Nitric Acid provides, in addition to common physical constants, a general description including typical appearance, applications, change in state (approximate), 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: Appearance, Assay, Color (APHA), Residue after Ignition, Chloride, Sulfate, Arsenic, Heavy Metals, and Iron.
HNO3
Formula Wt 63.01
CAS No. 7697-37-2
Note: This material may darken during storage as a result of photochemical reactions.
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . . Density . . . . . . . . . . . . . . . . pKa . . . . . . . . . . . . . . . . . .
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clear, colorless liquid, fuming in moist air; with a characteristic odor solvent; acidifier; trace metal standard matrix boiling point, 83 °C very soluble 1.50 –2.3
SPECIFICATIONS Appearance . . . . . . . . . . . . . . . . . . . . . . . . Colorless and free from suspended matter or sediment Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68.0–70.0% HNO3 Maximum Allowable Color (APHA) . . . . . . . . . . . . . . . . . . . . . . . 10 Residue after ignition. . . . . . . . . . . . . . . . . . 5 ppm Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.5 ppm Sulfate (SO4) . . . . . . . . . . . . . . . . . . . . . . . 1 ppm
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4242 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Arsenic (As) . . . . . . . . . . . . . . . . . . . . . . . . 0.01 ppm Heavy metals (as Pb) . . . . . . . . . . . . . . . . . . 0.2 ppm Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 0.2 ppm
TESTS Appearance Mix the acid in the original container, transfer 10 mL to a test tube (20 mm × 150 mm), and compare with distilled water in a similar tube. The liquids should be equally clear and free from suspended matter.
Assay (By acid–base titrimetry). Tare a small glass-stoppered flask containing about 15 mL of water. Quickly pipette about 2 mL of the sample under the surface, stopper, cool, and weigh accurately. Dilute with about 40 mL of water, add 0.15 mL of methyl orange indicator solution, and titrate with 1 N sodium hydroxide volumetric solution. One milliliter of 1 N sodium hydroxide corresponds to 0.06301 g of HNO3.
Color (APHA) [Part 2: Measurement of Physical Properties; Color (APHA); Procedure for Color (APHA)].
Residue after Ignition To 200 g (140 mL) in a tared, preconditioned dish add 0.05 mL of sulfuric acid, evaporate as far as possible on low heat (~100 °C), and heat gently to volatilize the excess sulfuric acid. Finally, ignite at 800 ± 25 °C for 15 min.
Chloride Dilute 20 g (14 mL) with 10 mL of water, and add 1 mL of silver nitrate reagent solution. Prepare a standard containing 0.01 mg of chloride ion (Cl) in 20 mL of water, and add 1 mL of silver nitrate reagent solution. Evaporate the solutions to dryness on a hot plate (~100 °C). Dissolve the residues in 0.5 mL of ammonium hydroxide, dilute with water to 20 mL, and add 1.5 mL of nitric acid. Any turbidity in the solution of the sample should not exceed that in the standard.
Sulfate [Part 2: Colorimetry and Turbidimetry; Sulfate; Procedure for Sulfate, Method 3]. Use 50 g (35 mL) of sample.
Arsenic [Part 2: Colorimetry and Turbidimetry; Arsenic]. To 300 g (210 mL) in a 250 mL beaker, add 5 mL of sulfuric acid, and evaporate on a hot plate (~100 °C) to a volume of about 5 mL. Transfer the beaker to a hot plate in a fume hood, and heat to dense fumes of sulfur trioxide. Cool, cautiously wash down the beaker with about 10 mL of water, evaporate again to dense fumes of sulfur trioxide, and continue the fuming for 15 min. Cool, wash down the beaker with about 10 mL of water, and repeat the fuming. Cool, cautiously wash the solution into a generator flask with sufficient water to make 35 mL, add 0.5 g of hydrazine sulfate, and proceed as described. For the standard, use 0.003 mg of arsenic ion (As).
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4242 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]. To 100 g (70 mL) in a beaker, add 1 mL of 1% sodium carbonate reagent solution, evaporate to dryness on a hot plate (~100 °C), dissolve the residue in about 20 mL of water, and dilute with water to 25 mL.
Iron [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. Evaporate 50 g (35 mL) to dryness, dissolve the residue in 2 mL of hydrochloric acid, dilute with water to 50 mL, and use the solution without further acidification.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4242 ACS Reagent Chemicals, Part 4
