Sodium Bismuthate - American Chemical Society

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

Sodium Bismuthate 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 11, 2017 | http://pubs.acs.org Publication Date (Web): February 28, 2017 | doi: 10.1021/acsreagents.4331

ABSTRACT This monograph for Sodium Bismuthate provides, in addition to common physical constants, a general description including typical appearance, applications, 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, Chloride, Manganese, and Oxidizing Efficiency.

NaBiO3

Formula Wt 279.97

CAS No. 12232-99-4

GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . yellow to brown solid Applications . . . . . . . . . . . . . . . . . . . . . . . . oxidizer; determination of manganese in iron and steel Aqueous solubility . . . . . . . . . . . . . . . . . . . . insoluble in cold water; decomposes in hot water

SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥80.0% NaBiO3 Oxidizing efficiency . . . . . . . . . . . . . . . . . . . ≥99.6% Maximum Allowable Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.002% Manganese (Mn) . . . . . . . . . . . . . . . . . . . . . 5 ppm

TESTS Assay (By titration of oxidizing power). Weigh accurately about 0.7 g, place in a flask, add 50.0 mL of 0.1 N ferrous ammonium sulfate volumetric solution, and stopper the flask. Transfer 50.0 mL of the ferrous ammonium sulfate to another flask, and stopper the flask. Allow each flask to stand for 30 min, shaking frequently, and titrate the ferrous ammonium sulfate in each with 0.1 N potassium permanganate volumetric solution. The difference in the volume of permanganate consumed in the

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A

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

DOI:10.1021/acsreagents.4331 ACS Reagent Chemicals, Part 4

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

two titrations is equivalent to the sodium bismuthate. One milliliter of 0.1 N potassium permanganate corresponds to 0.01400 g of NaBiO3.

Chloride Add 1.0 g to 25 mL of water, heat to boiling, and keep at the boiling temperature for 10 min. Dilute with water to 50 mL, and filter through a chloride-free filter. To 25 mL of the filtrate, add 0.15 mL of 30% hydrogen peroxide to clear the solution, and then 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.


Manganese Dissolve 2.0 g in 35 mL of dilute nitric acid (5:2), heat to boiling, and boil gently for 5 min. Prepare a standard containing 0.01 mg of manganese ion (Mn) in 35 mL of dilute nitric acid (5:2). To each, add 5 mL of sulfuric acid, 5 mL of phosphoric acid, and 0.5 mL of sulfurous acid. Boil gently to expel oxides of nitrogen, cool the solutions to 15 °C, and add 0.5 g of sodium bismuthate to each. Allow to stand for 5 min with occasional stirring, dilute each with 25 mL of water, and filter through a filter other than paper. Any pink color in the solution of the sample should not exceed that in the standard.

Oxidizing Efficiency

For the Determination of Oxidizing Efficiency

M a n g a n e s e M e t a l f o r U s e a s O x i d i m e t r i c S t a n d a r d . Assay a selected lot of commercial high-purity electrolytic manganese, previously screened through a U.S. number 10 and retained on a U.S. number 20 screen, by determining the concentration of impurities. Evaluate metals at levels below 0.03% by the spectrographic semiquantitative method, which can be done with sufficient accuracy. Evaluate metals at higher concentrations by suitable quantitative methods; determine carbon and sulfur by classical combustion methods. Determine oxygen, hydrogen, and nitrogen by vacuum fusion analysis, employing a 25 g iron bath containing 2–3 g of tin. Place the sample in a tin capsule and drop it into the bath, which is held at 1500–1550 °C. Analyze up to three samples before discarding the bath. The assay of the manganese metal for use as an oxidimetric standard should not be less than 99.8% Mn. (Because of the tendency of the metal to react with oxygen, it must be stored in a tightly sealed container after the assay has been performed.)

To 0.20 g of oxidimetric standard manganese metal in a 1 L conical flask, add 15 mL of dilute nitric acid (1:3), and heat cautiously until the manganese is dissolved. Add 8 mL of 70% perchloric acid, and boil gently until the acid fumes strongly and manganese dioxide begins to separate. Cool, add 5 mL of water and 25 mL of dilute nitric acid (1:3), and boil for several minutes to expel free chlorine. Add sufficient sulfurous acid or sodium nitrite solution to just dissolve the manganese dioxide. Boil the solution to expel completely the oxides of nitrogen. Cool to room temperature, add 225 mL of colorless, dilute nitric acid (2:5) and sufficient water to bring the total volume to 250 mL, and cool to 10–15 °C. Add 7 g of sodium bismuthate (weighed to the nearest 10 mg) to the flask, agitate briskly for 1 min, dilute with 250 mL of cold water (10–15 °C), and filter immediately through a fine-porosity fritted glass filter (pretreat the frit in hot nitric acid and then wash it free of acid with hot water). The filter can be washed free of manganese more readily if not allowed to run dry during the filtering and washing. Wash the filter with cold, freshly boiled dilute nitric acid (3:97) until the washings are entirely colorless, and immediately treat the filtrate and washings as directed in the next paragraph. Add 8.5 g of ferrous ammonium sulfate heptahydrate (weighed to the nearest mg) to the filtered solution of permanganic acid. Stir briskly. As soon as reduction is complete and all the salt is dissolved, add 0.01 M 1,10-phenanthroline indicator


B



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Monograph

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

solution, and titrate the excess of ferrous ion with 0.1 N potassium permanganate volumetric solution to a clear green color that persists for at least 30 s. Determine the manganese equivalent of the ferrous ammonium sulfate heptahydrate by titrating 1.75 g of the salt with the 0.1 N potassium permanganate volumetric solution in 500 mL of cold, dilute nitric acid that has been pretreated with 2 g of sodium bismuthate under the conditions described. Calculate the oxidizing efficiency of the sodium bismuthate as follows:


where A = milliliters of exactly 0.1 N potassium permanganate volumetric solution equivalent to the ferrous sulfate added; B = milliliters of exactly 0.1 N potassium permanganate required to titrate the excess ferrous ions; and C = grams of manganese used, taking into account the assay of the metal.


C



Sodium Bismuthate - American Chemical Society

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