Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Ceric Ammonium Sulfate Dihydrate (Ammonium Tetrasulfatocerate Dihydrate) 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 Ceric Ammonium Sulfate Dihydrate provides, in addition to common physical constants, a general description including typical appearance and applications. The monograph also details the following specifications and corresponding tests for verifying that a substance meets ACS Reagent Grade specifications including: Assay, Insoluble in Dilute Sulfuric Acid, Phosphate, and Iron.
(NH4)4Ce(SO4)4·2H2O
Formula Wt 632.51
CAS No. 10378-47-9
GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . orange-yellow solid Applications . . . . . . . . . . . . . . . . . . . . . . . . preparation of cerium IV oxidimetric solutions
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥94% (NH4)4Ce(SO4)4 · 2H2O Maximum Allowable Insoluble in dilute sulfuric acid. . . . . . . . . . . . 0.05% Phosphate (PO4) . . . . . . . . . . . . . . . . . . . . . 0.03% Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 0.01%
TESTS Assay (By titration of the oxidative capacity of cerium IV). Weigh accurately 2.4–2.5 g, and place in a beaker. Cover with 10 mL of water, and add cautiously 5 mL of sulfuric acid. Stir thoroughly, and add water to complete dissolution. Dilute to 75–100 mL
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4087 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
with water, add 0.05 mL of 0.025 M ferroin indicator solution, and titrate with 0.1 N ferrous ammonium sulfate to the red end point. One milliliter of 0.1 N ferrous ammonium sulfate corresponds to 0.06326 g of (NH4)4Ce(SO4)4 · 2H2O.
Insoluble in Dilute Sulfuric Acid To 2.5 g, add 5 mL of sulfuric acid, stir, and then cautiously add 90 mL of water to dissolve. Heat to boiling, and digest on a hot plate (~100 °C) for 1 h. Filter through a tared filtering crucible, and wash thoroughly, first with 2% sulfuric acid, then with water. Dry at 105 °C.
Phosphate [Part 2: Colorimetry and Turbidimetry; Phosphate; Procedure for Phosphate, Method 2 (Extracted Molybdenum Blue)]. Dissolve 0.75 g by adding 1 mL of sulfuric acid and stirring in 30 mL of water. Add hydrogen peroxide dropwise until just colorless, boil to destroy the excess peroxide, cool, and dilute to 50 mL. Dilute a 2 mL aliquot to 60 mL, and adjust the pH to between 2 and 3 (using pH paper) with ammonium hydroxide. Note: This neutralization must avoid the formation of a precipitate, which would void the test.
Add 0.5 g of ammonium molybdate, and adjust the pH to 1.8 (using a pH meter) with 10% hydrochloric acid. Heat to boiling and cool to room temperature. Dilute with water to 90 mL, add 10 mL of hydrochloric acid, and continue as described. Carry along a standard containing 0.01 mg of phosphate ion (PO4) in 2.0 mL of sulfuric acid (1:29) treated as the 2.0 mL aliquot of the sample.
Iron [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 2 (Hydroxylamine and 1,10-Phenanthroline)]. Dissolve 1 g by adding 2 mL of sulfuric acid and stirring in 30 mL of water. Add dropwise 3% hydrogen peroxide until the color disappears. For the standard, add 0.1 mg of iron to 30 mL of water containing 2 mL of sulfuric acid and the same volume of hydrogen peroxide used in the test. Dilute the standard and sample each to 100 mL, and use 10 mL aliquots.
© 2017 American Chemical Society
B
DOI:10.1021/acsreagents.4087 ACS Reagent Chemicals, Part 4
