Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Barium Hydroxide Octahydrate 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
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ABSTRACT This monograph for Barium Hydroxide Octahydrate 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, Carbonate, Insoluble in Dilute Hydrochloric Acid, Chloride, Sulfide, Calcium, Potassium, Sodium, Strontium, Heavy Metals, and Iron.
Ba(OH)2 · 8H2O
Formula Wt 315.46
CAS No. 12230-71-6
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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colorless or white solid that absorbs carbon dioxide from air carbonate-free base in alkalimetry melting point, 78 °C 7 g per 100 mL at 20 °C
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥98.0% Ba(OH)2 · 8H2O Maximum Allowable Carbonate (as BaCO3). . . . . . . . . . . . . . . . . . 2.0% Insoluble in dilute hydrochloric acid . . . . . . . . 0.01% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.001% Sulfide (S) . . . . . . . . . . . . . . . . . . . . . . . . . Passes test Calcium (Ca) . . . . . . . . . . . . . . . . . . . . . . . 0.05% Potassium (K) . . . . . . . . . . . . . . . . . . . . . . . 0.01% Sodium (Na) . . . . . . . . . . . . . . . . . . . . . . . . 0.01% Strontium (Sr) . . . . . . . . . . . . . . . . . . . . . . 0.8% Heavy metals (as Pb) . . . . . . . . . . . . . . . . . . 5 ppm Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 0.001%
© 2017 American Chemical Society
A
ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4048 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Assay
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(By acid–base titrimetry). Weigh accurately 4–5 g sample, and dissolve in about 200 mL of carbon dioxide-free water. Add 0.10 mL of phenolphthalein indicator solution, and titrate with 1 N hydrochloric acid volumetric solution. Reserve this solution for the determination of carbonate. One milliliter of 1 N hydrochloric acid corresponds to 0.1577 g of Ba(OH)2 · 8H2O.
Carbonate To the solution reserved from the test for assay, add 5.00 mL of 1 N hydrochloric acid, heat to boiling, boil gently to expel all of the carbon dioxide, and cool. Add 0.10 mL of methyl orange indicator solution, and titrate the excess acid with 1 N sodium hydroxide volumetric solution. Each milliliter of 1 N hydrochloric acid consumed corresponds to 0.09867 g of BaCO3.
Insoluble in Dilute Hydrochloric Acid Dissolve 10 g in 100 mL of dilute hydrochloric acid (1:9). Heat the solution to boiling, then digest in a covered beaker on a hot plate (~100 °C) for 1 h. Filter through a tared, preconditioned filtering crucible, wash thoroughly, and dry at 105 °C.
Chloride Dissolve 2.0 g in 25 mL of water, add 0.05 mL of phenolphthalein indicator solution, and neutralize with nitric acid. If the solution is not perfectly clear, filter it through a chloride-free filter, and dilute the filtrate with water to 50 mL. To 25 mL of the solution, 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.
Sulfide Dissolve 1.0 g in 8 mL of warm water and add 0.25 mL of alkaline lead solution (prepared by adding 10% sodium hydroxide solution to a 10% lead acetate solution until the precipitate is redissolved) and 2 mL of glacial acetic acid. No darkening should occur. (Limit about 0.001%.)
Calcium, Potassium, Sodium, and Strontium (By flame AAS, [Part 2: Trace and Ultratrace Elemental Analysis; Atomic Absorption Spectroscopy; Analysis; Procedure for Flame AAS]).
© 2017 American Chemical Society
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ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4048 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
For the Determination of Calcium, Potassium, Sodium, and Strontium
S a m p l e S t o c k S o l u t i o n A . Dissolve 10.0 g of sample in water in a beaker, add 5 mL of nitric acid, and transfer to a 100 mL volumetric flask. Dilute to the mark with water (1 mL = 0.10 g). S a m p l e S t o c k S o l u t i o n B . Pipette 10.0 mL of sample stock solution A into a 100 mL volumetric flask, and dilute to the mark with water (1 mL = 0.01 g). Add 2.0 mL of a 2.5% potassium chloride reagent solution to the flask for calcium and strontium.
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For the Determination of Calcium, Potassium, Sodium, and Strontium
Element
Wavelength (nm)
Sample Wt (g)
Standard Added (mg)
Flame Type*
Background Correction
Ca
422.7
0.04
0.02; 0.04
N/A
No
K
766.5
0.10
0.01; 0.02
A/A
No
Na
589.0
0.05
0.005; 0.01
A/A
No
Sr
460.7
0.01
0.04; 0.08
N/A
No
*A/A is air/acetylene; N/A is nitrous oxide/acetylene.
Heavy Metals [Part 2: Colorimetry and Turbidimetry; Heavy Metals (as Lead); Procedure for Heavy Metals, Method 1]. To 5.0 g in a 150 mL beaker, add 25 mL of water, mix, and cautiously add 10 mL of hydrochloric acid. Evaporate to dryness on a hot plate (~100 °C), dissolve the residue in about 2 mL of water, and dilute with water to 25 mL. For the control, treat 1.0 g of the sample and 0.02 mg of lead ion (Pb) exactly as the 5.0 g of sample.
Iron Dissolve 1.0 g in 40 mL of water. For the standard, add 0.01 mg of iron ion (Fe) to 40 mL of water. Add 2.5 mL of hydrochloric acid to each, dilute with water to 50 mL, and add 0.10 mL of 0.1 N potassium permanganate solution. Allow to stand for 5 min, and add 3 mL of ammonium thiocyanate reagent solution. Any red color in the solution of the sample should not exceed that in the standard.
© 2017 American Chemical Society
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ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4048 ACS Reagent Chemicals, Part 4
