Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Ammonium Oxalate Monohydrate (Ethanedioic Acid, Diammonium Salt Monohydrate) 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 Ammonium Oxalate Monohydrate 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, Insoluble Matter, Residue after Ignition, Chloride, Sulfate, Heavy Metals, and Iron.
(COONH4)2 · H2O
Formula Wt 142.11
CAS No. 6009-70-7
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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colorless solid determination of calcium, lead, and rare earth metals decomposes at about 128 °C 5 g in 100 mL at 20 °C
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99.0–101.0% (COONH4)2 · H2O Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.005% Residue after ignition. . . . . . . . . . . . . . . . . . 0.02% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.002% Sulfate (SO4) . . . . . . . . . . . . . . . . . . . . . . . 0.002% Heavy metals (as Pb) . . . . . . . . . . . . . . . . . . 5 ppm Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 2 ppm
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4030 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Assay (By oxidation–reduction titration of oxalate). Transfer 5.0 g of previously crushed sample, accurately weighed, to a 500 mL volumetric flask. Dissolve it in water, dilute with water to volume, and mix. Pipette 25.0 mL of the solution into 70 mL of water and 5 mL of sulfuric acid in a beaker. Titrate slowly with 0.1 N potassium permanganate until about 25 mL has been added, then heat the mixture to about 70 °C, and complete the titration. One milliliter of 0.1 N potassium permanganate corresponds to 0.007106 g of (COONH4)2 · H2O.
Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Use 20.0 g dissolved in 400 mL of hot water.
Residue after Ignition [Part 2: Gravimetric Methods; Residue after Ignition]. Ignite 5.0 g.
Chloride Dissolve 2.0 g in water plus 10 mL of nitric acid, filter if necessary through a chloride-free filter, and dilute with water to 100 mL. To 25 mL of the solution, add 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.
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For the Determination of Sulfate, Heavy Metals, and Iron
S a m p l e S o l u t i o n A . Digest 20.0 g of sample plus 10 mL of 1% sodium carbonate reagent solution with 40 mL of nitric acid plus 35 mL of hydrochloric acid in a covered beaker on a hot plate (~100 °C) until no more bubbles of gas are evolved. Remove the cover, and evaporate until a small amount of crystals forms in the beaker. Add 10 mL of 30% hydrogen peroxide, cover the beaker, and digest on the hot plate until reaction ceases. Add an additional 10 mL of 30% hydrogen peroxide, re-cover the beaker, digest on a hot plate (~100 °C) until reaction ceases, remove the cover, and evaporate to dryness. Add 5 mL of dilute hydrochloric acid (1:1), cover, digest on the hot plate for 15 min, remove the cover, and evaporate to dryness. Dissolve the residue in about 50 mL of water, filter if necessary, and dilute with water to 100 mL (1 mL = 0.2 g). B l a n k S o l u t i o n B . Prepare a similar solution containing the quantities of reagents used in preparing sample solution A and treated in the identical manner.
Sulfate† [Part 2: Colorimetry and Turbidimetry; Sulfate; Procedure for Sulfate, Method 1]. Use 12.5 mL of sample solution A (2.5 g sample). Use 12.5 mL of blank solution B to prepare the standard solution.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4030 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Heavy Metals
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[Part 2: Colorimetry and Turbidimetry; Heavy Metals (as Lead); Procedure for Heavy Metals, Method 1]. Dilute 20 mL of sample solution A (4 g sample) with water to 25 mL. Use 20 mL of blank solution B to prepare the standard solution.
Iron† [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. Use 25 mL of sample solution A (5 g sample). Prepare the standard solution from 25 mL of blank solution B.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4030 ACS Reagent Chemicals, Part 4
