Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Ammonium Fluoride 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
Downloaded by CORNELL UNIV on June 20, 2017 | http://pubs.acs.org Publication Date (Web): February 28, 2017 | doi: 10.1021/acsreagents.4023
ABSTRACT This monograph for Ammonium Fluoride 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.
NH4F
Formula Wt 37.04
CAS No. 12125-01-8
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
. . . .
. . . .
. . . .
. . . .
. . . .
. . . .
. . . .
. . . .
. . . .
. . . .
. . . .
colorless or white, deliquescent solid etchant; extracting agent sublimes on heating 100 g in 100 mL at 0 °C
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥98.0% NH4F
Insoluble matter . . . . Residue after ignition. Chloride (Cl) . . . . . . Sulfate (SO4) . . . . . . Heavy metals (as Pb) . Iron (Fe) . . . . . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
© 2017 American Chemical Society
Maximum Allowable 0.005% 0.01% 0.001% 0.005% 5 ppm 5 ppm
A
ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4023 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Assay (By alkalimetry for ammonium). Weigh accurately about 1.0 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 volumetric solution, 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. One milliliter of 1 N sodium hydroxide corresponds to 0.03704 g of NH4F.
Downloaded by CORNELL UNIV on June 20, 2017 | http://pubs.acs.org Publication Date (Web): February 28, 2017 | doi: 10.1021/acsreagents.4023
Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Use 20 g dissolved in 200 mL of hot water.
Residue after Ignition [Part 2: Gravimetric Methods; Residue after Ignition]. Ignite 10 g in a tared, preconditioned platinum crucible or dish.
Chloride Dissolve 1.0 g sample and 1.0 g boric acid in a mixture of 20 mL of water and 2 mL of nitric acid in a platinum dish. Add 1 mL of silver nitrate reagent solution to the sample solution, and mix. Allow to stand for 5 min protected from sunlight, then add 10 mL of water. 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.
Sulfate [Part 2: Colorimetry and Turbidimetry; Sulfate; Procedure for Sulfate, Method 2]. Use 10 mL of hydrochloric acid in a platinum dish, and perform four evaporations.
Heavy Metals [Part 2: Colorimetry and Turbidimetry; Heavy Metals (as Lead); Procedure for Heavy Metals, Method 1]. Dissolve 5.0 g in about 25 mL of water, add 2 g of sodium acetate, and dilute with water to 30 mL. Adjust the pH with short-range pH paper. Use 1.0 g of sample and 2 g of sodium acetate to prepare the control solution.
Iron [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. Treat 2.0 g in a platinum dish with 10 mL of dilute hydrochloric acid (1:1), and evaporate on a hot plate (~100 °C) to dryness. Repeat the evaporation with a second portion of the dilute acid. Warm the residue with 2 mL of hydrochloric acid, dilute with water to 50 mL, and use this solution without further acidification. Prepare the standard from the residue remaining from the evaporation of 10 mL of hydrochloric acid.
© 2017 American Chemical Society
B
ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4023 ACS Reagent Chemicals, Part 4
