Sulfuric Acid - ACS Publications - American Chemical Society

Monograph pubs.acs.org/doi/book/10.1021/acsreagents

Sulfuric 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

Downloaded by CORNELL UNIV on May 13, 2017 | http://pubs.acs.org Publication Date (Web): February 28, 2017 | doi: 10.1021/acsreagents.4387

ABSTRACT This monograph for Sulfuric 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, Nitrate, Ammonium, Substances Reducing Permanganate, Arsenic, Heavy Metals, Iron, and Mercury.

H2SO4

Formula Wt 98.07

CAS No. 7664-93-9

GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . . Density . . . . . . . . . . . . . . . . pKa . . . . . . . . . . . . . . . . . .

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clear, colorless liquid digestion of organic matter; pH modification; titration of bases boiling point, 290 °C miscible; generates heat 1.84 ~ –3

SPECIFICATIONS Appearance . . . . . . . . . . . . . . . . . . . . . . . . Free from suspended or insoluble matter Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95.0–98.0% H2SO4 Maximum Allowable Color (APHA) . . . . . . . . . . . . . . . . . . . . . . . 10 Residue after ignition. . . . . . . . . . . . . . . . . . 5 ppm Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.2 ppm Nitrate (NO3) . . . . . . . . . . . . . . . . . . . . . . . 0.5 ppm Ammonium (NH4) . . . . . . . . . . . . . . . . . . . . 2 ppm Substances reducing permanganate (as SO2) . . . 2 ppm Arsenic (As) . . . . . . . . . . . . . . . . . . . . . . . . 0.01 ppm

© 2017 American Chemical Society

A

ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.

DOI:10.1021/acsreagents.4387 ACS Reagent Chemicals, Part 4

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pubs.acs.org/doi/book/10.1021/acsreagents

Heavy metals (as Pb) . . . . . . . . . . . . . . . . . . 1 ppm Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 0.2 ppm Mercury (Hg) . . . . . . . . . . . . . . . . . . . . . . . 5 ppb

TESTS Appearance Mix the material in the original container, pour 10 mL into 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, add about 1 mL of the sample, and weigh accurately. Cautiously add 30 mL of water, cool, 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 0.04904 g of H2SO4.

Color (APHA) [Part 2: Measurement of Physical Properties; Color (APHA); Procedure for Color (APHA)].

Residue after Ignition [Part 2: Gravimetric Methods; Residue after Ignition]. Evaporate 200.0 g (110 mL) to dryness in a tared, preconditioned platinum dish, and ignite at 800 ± 25 °C for 15 min.

Chloride Place 40 mL of water in each of three beakers. To one, carefully add 50.0 g (27.2 mL) of sample, and to the others, carefully add 50.0 g (27.2 mL) of chloride-free sulfuric acid. To the second beaker, add 0.01 mg of chloride ion (Cl). Cool to room temperature, mix, and to each beaker, add 1 mL of nitric acid and 1 mL of silver nitrate reagent solution. Mix well, and if necessary, make the volume of each solution identical by adding water. Transfer equal portions of each solution to Nessler tubes. After 10 min, any turbidity of the sample solution should not exceed that of the standard. The blank should be free of turbidity. The comparison can be aided by use of a nephelometer.

Nitrate [Part 2: Colorimetry and Turbidimetry; Nitrate; Procedure for Nitrate, Method 1 (Brucine Sulfate)].

For the Determination of Nitrate

S a m p l e S o l u t i o n A . Cautiously add 40.0 g (22 mL) to 2.0 mL of water, dilute to 50 mL with brucine sulfate reagent solution, and mix. C o n t r o l S o l u t i o n B . Cautiously add 40.0 g (22 mL) to 2.0 mL of nitrate ion (NO3) standard solution, dilute to 50 mL with brucine sulfate reagent solution, and mix.


B



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Continue with the procedure, starting with the preparation of blank solution C.

Ammonium Add 2.5 g (1.35 mL) of sample to 25 mL of water. Cautiously add 20 mL of freshly boiled 10% sodium hydroxide solution while cooling the solution. Transfer to a 50 mL Nessler tube, add 2 mL of Nessler reagent, and dilute to volume with water. The color produced should not exceed that produced by 0.005 mg of ammonium ion treated identically.

Substances Reducing Permanganate Cool 50 mL of water in a 150 mL beaker in an ice bath. Slowly add 25 mL (46 g) of sample while stirring and keeping the solution cool. Remove from the bath, and add 0.30 mL of 0.01 N potassium permanganate. The solution should remain pink for at least 5 min.


Arsenic [Part 2: Colorimetry and Turbidimetry; Arsenic]. To 300.0 g (165 mL), add 3 mL of nitric acid, and evaporate on a hot plate (~100 °C) to about 10 mL. Cool, cautiously dilute with about 20 mL of water, and evaporate just to dense fumes of sulfur trioxide. Cool, and cautiously wash the solution into a generator flask with the aid of 50 mL of water. Omit the addition of dilute sulfuric acid. For the standard, use 0.003 mg of arsenic ion (As).

Heavy Metals [Part 2: Colorimetry and Turbidimetry; Heavy Metals (as Lead); Procedure for Heavy Metals, Method 1]. Add 20.0 g (11 mL) to about 10 mg of sodium carbonate dissolved in a small quantity of water. Heat over a low flame until nearly dry, then add 1 mL of nitric acid. Evaporate to dryness, add 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)]. Add 50.0 g (27 mL) to about 10 mg of sodium carbonate dissolved in a small quantity of water. Evaporate to dryness by heating on an electric hot plate. Cool, add 5 mL of dilute hydrochloric acid (1:1), cover with a watch glass, and digest on a hot plate (~100 °C) for 15 min. Cool, and dilute with water to 25 mL.

Mercury To each of two 125 mL conical flasks, add 20 mL of water and 5 mL of 4% potassium permanganate solution. For the sample, add to one flask, slowly and with cooling, 11.0 g (6.0 mL) of the sulfuric acid. For the control, add to the second flask 1.0 g (0.5 mL) of the sulfuric acid and 0.05 µg of mercury ion (Hg) [0.5 mL of a solution freshly prepared by diluting 1 mL of mercury ion (Hg) standard solution, with water to 500 mL]. Place both flasks on a hot plate (~100 °C) for 15 min, then cool to room temperature. Determine the mercury in each by CVAAS [Part 2: Trace and Ultratrace Elemental Analysis; Mercury Determination by CVAAS], using 1 mL of 10% hydroxylamine hydrochloride reagent solution and 2 mL of 10% stannous chloride reagent solution for the reduction. Any mercury found in the sample should not exceed that in the control.


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Sulfuric Acid - ACS Publications - American Chemical Society

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