Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Ammonium Sulfate 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 Ammonium Sulfate 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, Residue after Ignition, Chloride, Nitrate, Phosphate, Heavy Metals, and Iron.
(NH4)2SO4
Formula Wt 132.14
CAS No. 7783-20-2
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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colorless powder or solid freezing mixtures melting point, 280 °C with decomposition 75 g in 100 mL at 20 °C
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥99.0% (NH4)2SO4 pH of a 5% solution at 25.0 °C . . . . . . . . . . . . 5.0–6.0 Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.005% Residue after ignition. . . . . . . . . . . . . . . . . . 0.005% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 5 ppm Nitrate (NO3) . . . . . . . . . . . . . . . . . . . . . . . 0.001% Phosphate (PO4) . . . . . . . . . . . . . . . . . . . . . 5 ppm Heavy metals (by ICP–OES) . . . . . . . . . . . . . . 5 ppm Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 5 ppm
© 2017 American Chemical Society
A
ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4035 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Assay (By alkalimetry for ammonium). Weigh, to the nearest 0.1 mg, 2.5 g of sample, and dissolve in 50 mL of water in a 500 mL Erlenmeyer flask. Add exactly 50.0 mL of 1 N sodium hydroxide, place a filter funnel loosely in the neck of the flask, and boil until all the ammonia is expelled (about 10–15 min) as determined with litmus paper. Cool, and add 0.15 mL of thymol blue indicator solution. Titrate the excess sodium hydroxide with 1 N sulfuric acid volumetric solution. One milliliter of 1 N sodium hydroxide corresponds to 0.06607 g of (NH4)2SO4.
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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 20 g dissolved in 200 mL of water.
Residue after Ignition [Part 2: Gravimetric Methods; Residue after Ignition]. Ignite 20 g.
Chloride [Part 2: Colorimetry and Turbidimetry; Chloride]. Use 2.0 g.
Nitrate [Part 2: Colorimetry and Turbidimetry; Nitrate; Procedure for Nitrate, Method 1 (Brucine Sulfate)]. For sample solution A, use 1.0 g. For control solution B, use 1.0 g and 1 mL of nitrate ion (NO3) standard solution.
Phosphate [Part 2: Colorimetry and Turbidimetry; Phosphate; Procedure for Phosphate, Method 1 (Direct Molybdenum Blue)]. Dissolve 4.0 g in 25 mL of 0.5 N sulfuric acid.
Heavy Metals ([Part 2: Trace and Ultratrace Elemental Analysis; Inductively Coupled Plasma−Optical Emission Spectroscopy (ICP–OES); Calculation of Heavy Metals (by ICP–OES) Results], by ICP–OES). Use 2.0 g sample.
Iron [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. Use 2.0 g.
© 2017 American Chemical Society
B
ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4035 ACS Reagent Chemicals, Part 4
