Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Lead Dioxide (Lead(IV) Oxide) 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 Lead Dioxide 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, Acid-Insoluble Matter, Carbon Compounds, Chloride, Nitrate, Sulfate, Manganese, Calcium, Copper, Potassium, and Sodium.
PbO2
Formula Wt 239.20
CAS No. 1309-60-0
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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dark brown solid oxidizing agent melting point, 290 °C, with decomposition insoluble
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥97.0% PbO2 Maximum Allowable Acid-insoluble matter. . . . . . . . . . . . . . . . . . 0.2% Carbon compounds (as C) . . . . . . . . . . . . . . . 0.04% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.002% Nitrate (NO3) . . . . . . . . . . . . . . . . . . . . . . . 0.02% Sulfate (SO4) . . . . . . . . . . . . . . . . . . . . . . . 0.05% Manganese (Mn) . . . . . . . . . . . . . . . . . . . . . 5 ppm Calcium (Ca) . . . . . . . . . . . . . . . . . . . . . . . 0.02% Copper (Cu) . . . . . . . . . . . . . . . . . . . . . . . . 0.05%
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4189 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Potassium (K) . . . . . . . . . . . . . . . . . . . . . . . 0.05% Sodium (Na) . . . . . . . . . . . . . . . . . . . . . . . . 0.1%
TESTS Assay (By titration of oxidizing power). Dissolve 25 g of sodium chloride in 100 mL of water in a stoppered flask. Add 2 g of potassium iodide and 20 mL of hydrochloric acid. Add, accurately weighed, about 0.25 g of finely powdered sample, and stir until the sample is dissolved. Titrate the liberated iodine with 0.1 N sodium thiosulfate volumetric solution, adding 3 mL of starch indicator solution near the end of the titration. One milliliter of 0.1 N sodium thiosulfate corresponds to 0.01196 g of PbO2.
Acid-Insoluble Matter To 1.0 g, add 25 mL of water and 3 mL of nitric acid. Add carefully with stirring 5 mL of 30% hydrogen peroxide or more, if needed, to dissolve all the lead dioxide. Filter through a tared, preconditioned filtering crucible, wash thoroughly, and dry at 105 °C.
Carbon Compounds This procedure uses induction heating of the sample and a conductometric measurement of the evolved carbon dioxide. Transfer 1.0 g and one tin capsule to a combustion crucible. Add 1.5 g each of iron and copper accelerator. Ignite in an induction furnace in a stream of carbon dioxide-free oxygen until combustion is complete. Pass the effluent gas through an approximately 0.1% solution of barium hydroxide. Measure the change in conductance, in mhos, by using a suitable cell and detection system. Subtract the reading from a blank, and calculate the carbon content of the sample from a calibration curve. Prepare the calibration curve as follows: transfer 0, 10, 25, 75, and 100 µL of carbon standard solution (1 µL = 4 µg of carbon) to tin capsules. Evaporate the solutions to dryness in the capsules at 80 °C. Transfer the capsules to combustion crucibles, add the accelerators, ignite, and measure the conductance under the same conditions as described for running the sample. Subtract the reading of the blank from that of each of the standards, and plot the calibration curve as mhos versus micrograms of carbon.
Chloride [Part 2: Colorimetry and Turbidimetry; Chloride]. Dissolve 2.0 g in 20 mL of water plus 2 mL of glacial acetic acid and 2 mL of 30% hydrogen peroxide. Filter through a chloride-free filter, dilute with water to 100 mL, and use 25 mL of this solution.
Nitrate [Part 2: Colorimetry and Turbidimetry; Nitrate; Procedure for Nitrate, Method 1 (Brucine Sulfate)]. Dissolve 0.25 g in a test tube containing 10 mL of water, 1 mL of glacial acetic acid, and 0.5 mL of 30% hydrogen peroxide. Pass sulfur dioxide through the solution to precipitate the lead, filter, wash with two 2 mL portions of water, and dilute the filtrate with water to 20 mL.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4189 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
For the Determination of Nitrate
S a m p l e S o l u t i o n A . To 4.0 mL of the filtrate in a test tube, add 1 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 . To 4.0 mL of the filtrate in a test tube, add 1 mL of nitrate ion (NO3) standard solution, dilute to 50 mL with brucine sulfate reagent solution, and mix.
Continue with the procedure, starting with the preparation of blank solution C.
Sulfate Decompose 2.0 g with 10 mL of hydrochloric acid and 3 mL of nitric acid, and evaporate to dryness on a hot plate (~100 °C). Add 25 mL of water and 2 g of sodium carbonate, and digest on a hot plate (~100 °C) for several hours, with occasional stirring. Dilute with water to 100 mL, and filter. Neutralize the filtrate with hydrochloric acid and add an excess of 1 mL of the acid. Heat to boiling, add 5 mL of 12% barium chloride reagent solution, digest in a covered beaker on the hot plate for 2 h, and allow to stand for at least 8 h. Filter, using a fine ashless paper, wash thoroughly, and ignite. Correct for the weight obtained in a complete blank test.
Manganese Add 10 g to 15 mL of dilute nitric acid (1:1). Add carefully, with stirring, about 10 mL of 30% hydrogen peroxide—or more, if necessary—to dissolve all of the lead dioxide. Evaporate nearly to dryness, cool, add 20 mL of dilute sulfuric acid (1:1), and evaporate to dense fumes of sulfur trioxide. Cool, cautiously dilute to 100 mL with water, allow to settle, and filter. Dilute 20 mL of the filtrate with water to 50 mL, add 10 mL of nitric acid and 5 mL of phosphoric acid, and boil gently for 5 min. Cool slightly, add 0.25 g of potassium periodate, and again boil gently for 5 min. Any pink color should not exceed that produced by 0.01 mg of manganese in 50 mL of dilute sulfuric acid (1:9) treated exactly like the 50 mL of filtrate.
Calcium, Copper, Potassium, and Sodium (By flame AAS, [Part 2: Trace and Ultratrace Elemental Analysis; Atomic Absorption Spectroscopy; Analysis; Procedure for Flame AAS]).
For the Determination of Calcium, Copper, Potassium, and Sodium
S a m p l e S t o c k S o l u t i o n . Dissolve by warming 10.0 g of sample with a mixture of 20 mL of water and 15 mL of nitric acid. Cool to room temperature, transfer to a 100 mL volumetric flask, and dilute to the mark with water (1 mL = 0.1 g).
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4189 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
For the Determination of Calcium, Copper, Potassium, and Sodium
Element
Wavelength (nm)
Sample Wt (g)
Standard Added (mg)
Flame Type*
Background Correction
Ca
422.7
0.40
0.04; 0.08
N/A
No
Cu
324.8
0.10
0.025; 0.05
A/A
Yes
K
766.5
0.10
0.025; 0.05
A/A
No
Na
589.0
0.02
0.01; 0.02
A/A
No
*A/A is air/acetylene; N/A is nitrous oxide/acetylene.
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DOI:10.1021/acsreagents.4189 ACS Reagent Chemicals, Part 4
