Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Sodium Pyrophosphate Decahydrate (Diphosphoric Acid, Tetrasodium Salt, Decahydrate) 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 Sodium Pyrophosphate Decahydrate 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, pH of a 5% Solution at 25.0 °C, Insoluble Matter, Chloride, Sulfate, Nitrogen Compounds, Heavy Metals, and Iron.
Na4P2O7 • 10H2O
Formula Wt 446.06
CAS No. 13472-36-1
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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colorless solid fusion matrix melting point, 79 °C 10 g in 100 mL at 20 °C
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99.0–103.0% Na4P2O7 · 10H2O pH of a 5% solution at 25.0 °C . . . . . . . . . . . . 9.5–10.5 Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.01% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.002% Sulfate (SO4) . . . . . . . . . . . . . . . . . . . . . . . 0.005% Nitrogen compounds (as N) . . . . . . . . . . . . . . 0.001% Heavy metals (as Pb) . . . . . . . . . . . . . . . . . . 0.001% Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 0.001%
© 2017 American Chemical Society
A
DOI:10.1021/acsreagents.4367 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Assay (By acid–base titrimetry). Weigh accurately about 8.0 g, and dissolve in 100 mL of water. Titrate with 1 N hydrochloric acid volumetric solution to a green color with 0.15 mL of bromphenol blue indicator solution. One milliliter of 1 N hydrochloric acid corresponds to 0.2230 g of Na4P2O7 · 10H2O.
pH of a 5% Solution at 25.0 °C [Part 2: Direct Electrometric Methods; pH Potentiometry; pH Range; Procedure for pH of a 5% Solution at 25.0 °C].
Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Use 10.0 g dissolved in 150 mL of water.
Chloride [Part 2: Colorimetry and Turbidimetry; Chloride]. Use 0.50 g of sample and 3 mL of nitric acid.
Sulfate Dissolve 1.0 g in 15 mL of water, and add 5.0 mL of 10% hydrochloric acid (solution pH approximately 2). Filter through washed filter paper, and add 10 mL of water through the same filter. For control, add 0.05 mg of sulfate ion (SO4) in 20 mL of water, and add 1.0 mL of (1:19) hydrochloric acid. Dilute both to 35 mL with water, add 5.0 mL of 40% barium chloride solution, and mix. Observe turbidity after 10 min. Sample solution turbidity should not exceed that of the control solution.
Nitrogen Compounds [Part 2: Colorimetry and Turbidimetry; Nitrogen Compounds: Test for Ammonia, Amines, and Nitrogen Compounds Reduced by Aluminum]. Use 1.0 g. For the standard, use 0.01 mg of nitrogen ion (N).
Heavy Metals [Part 2: Colorimetry and Turbidimetry; Heavy Metals (as Lead); Procedure for Heavy Metals, Method 1]. Dissolve 3.0 g in about 20 mL of water, warming if necessary, add 8 mL of 2 N hydrochloric acid, and dilute with water to 42 mL. Use 35 mL to prepare the sample solution, and use the remaining 7.0 mL to prepare the control solution.
Iron [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 2 (Hydroxylamine and 1,10-Phenanthroline)]. Use 1.0 g.
© 2017 American Chemical Society
B
DOI:10.1021/acsreagents.4367 ACS Reagent Chemicals, Part 4
