Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Perchloric 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 Perchloric Acid provides, in addition to common physical constants, a general description including typical appearance, applications, and pKa. The monograph also details the following specifications and corresponding tests for verifying that a substance meets ACS Reagent Grade specifications including: Assay, Color (APHA), Residue after Ignition, Silicate, Phosphate, Chloride, Nitrogen Compounds, Sulfate, Heavy Metals, and Iron.
HClO4
Formula Wt 100.46
CAS No. 7601-90-3
Note: This specification applies to perchloric acid with nominal concentrations of 50%, 60%, or 70%.
GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . clear, colorless liquid Applications . . . . . . . . . . . . . . . . . . . . . . . . solvent for metals and ores; standard acid; oxidizer; nonaqueous titrimetry; wet ashing pKa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . < –10
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48.0–50.0% HClO4; 60.0–62.0% HClO4; 69.0–72.0% HClO4 Maximum Allowable Color (APHA) . . . . . . . . . . . . . . . . . . . . . . . 10 Residue after ignition. . . . . . . . . . . . . . . . . . 0.003% Silicate and phosphate (as SiO2) . . . . . . . . . . . 5 ppm Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.001% Nitrogen compounds (as N) . . . . . . . . . . . . . . 0.001% Sulfate (SO4) . . . . . . . . . . . . . . . . . . . . . . . 0.001% Heavy metals (as Pb) . . . . . . . . . . . . . . . . . . 1 ppm Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 1 ppm
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4257 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Note: All tests are written for 70% concentration. The densities of the 60% acid (1.54 g/mL) and the 50% acid (1.40 g/ mL) are less than the density of the 70% reagent (1.67 g/mL), and proper allowance should be made for this when measured volumes are taken for relevant tests.
Assay (By alkalimetric titration). Weigh accurately about 3 mL in a suitable flask, and dilute with water to 60 mL. Add 0.15 mL of phenolphthalein indicator solution, and titrate with 1 N sodium hydroxide volumetric solution. One milliliter of 1 N sodium hydroxide corresponds to 0.1005 g of HClO4.
Color (APHA) [Part 2: Measurement of Physical Properties; Color (APHA); Procedure for Color (APHA)].
Residue after Ignition [Part 2: Gravimetric Methods; Residue after Ignition]. To 67 g (42 mL) in a tared, preconditioned dish, add 1 mL of nitric acid, evaporate to dryness, and ignite at 600 ± 25 °C for 15 min.
Silicate and Phosphate Dilute 2.0 g (1.2 mL) with 50 mL of water in a platinum dish, add 1.0 g of sodium carbonate, and digest on a hot plate (~100 °C) for 15–30 min. Cool, add 5 mL of a 10% ammonium molybdate reagent solution, acidify with hydrochloric acid to about pH 4 (using indicator paper), and transfer to a beaker. Adjust the pH to 1.8 (using a pH meter) with dilute hydrochloric acid (1:9). Dilute with water to 90 mL, heat just to boiling, and cool to room temperature. Add 10 mL of hydrochloric acid, and dilute with water to 100 mL. Transfer to a separatory funnel, add 50 mL of 4-methyl-2-pentanone, shake vigorously, and allow to separate. Draw off and discard the aqueous phase. Wash the ketone layer three times with 20 mL portions of dilute hydrochloric acid (1:99), drawing off and discarding the aqueous layer each time. Add 10 mL of dilute hydrochloric acid (1:99), to which has just been added 0.2 mL of a freshly prepared 2% stannous chloride reagent solution. Shake vigorously, and allow to separate. Any blue color should not exceed that produced by 0.01 mg of silica and 1 g of sodium carbonate, treated exactly like the sample.
Chloride [Part 2: Colorimetry and Turbidimetry; Chloride]. Dilute 1 g (0.6 mL) with 25 mL of water.
Nitrogen Compounds [Part 2: Colorimetry and Turbidimetry; Nitrogen Compounds: Test for Ammonia, Amines, and Nitrogen Compounds Reduced by Aluminum]. Use 5 g (3.0 mL). For the standard, use 0.05 mg of nitrogen ion (N).
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4257 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Sulfate Dilute 32.0 g (20 mL) with water to 160 mL, and neutralize with ammonium hydroxide, using litmus paper as an indicator. Add 1 mL of hydrochloric acid, heat to boiling, add 5 mL of 12% barium chloride reagent solution, digest in a covered beaker on a hot plate (~100 °C) for 2 h, and allow to stand for at least 8 h. If a precipitate is formed, filter, wash thoroughly, and ignite. The weight of the precipitate should not be more than 0.0008 g greater than the weight obtained from a complete blank test, including the evaporated residue from a volume of ammonium hydroxide equal to that used to neutralize the sample.
†
For the Determination of Heavy Metals and Iron
S a m p l e S o l u t i o n A . To 40.0 g (25 mL), add 1 mL of nitric acid and 1 mL of 1% sodium carbonate reagent solution. Evaporate to dryness on a hot plate in a well-ventilated hood, dissolve the residue in 2 mL of 1 N acetic acid, and dilute with water to 40 mL (1 mL = 1.0 g).
Heavy Metals† [Part 2: Colorimetry and Turbidimetry; Heavy Metals (as Lead); Procedure for Heavy Metals, Method 1]. Dilute 20 mL of sample solution A (20 g sample) with water to 25 mL.
Iron† [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. Use 10 mL of sample solution A (10 g sample).
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4257 ACS Reagent Chemicals, Part 4
