Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Aluminum Potassium Sulfate Dodecahydrate 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 Aluminum Potassium Sulfate Dodecahydrate 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, Chloride, Ammonium, Heavy Metals, Iron, and Sodium.
AlK(SO4)2 · 12H2O
Formula Wt 474.37
CAS No. 7784-24-9
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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colorless solid buffer; flocculating reagent melting point, 92 °C 5.7 g in 100 mL at 0 °C; extremely soluble in hot water
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98.0–102.0% AlK(SO4)2 · 12H2O Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.005% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 5 ppm Ammonium (NH4) . . . . . . . . . . . . . . . . . . . . 0.005% Heavy metals (as Pb) . . . . . . . . . . . . . . . . . . 0.001% Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 0.001% Sodium (Na) . . . . . . . . . . . . . . . . . . . . . . . . 0.02%
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4011 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Assay (By indirect complexometric titration of AlIII). Weigh accurately 10 g, and transfer to a 250 mL volumetric flask. Dissolve in about 75 mL of water, add 5 mL of hydrochloric acid, dilute to volume with water, and mix. Place a 25.0 mL aliquot of this solution in a 250 mL beaker, add 50 mL of water, and mix. While stirring, add 40.0 mL of 0.1 M EDTA volumetric solution and 20 mL of ammonium acetate–acetic acid buffer solution. Heat the solution to near boiling for 5 min, and cool. (The pH should be 4.0–5.0 and should be maintained in that range by adding more buffer during the titration if necessary.) Add 50 mL of alcohol and 2 mL of dithizone indicator solution, and titrate the excess of EDTA with 0.1 M zinc chloride volumetric solution until the color changes from a green-violet to a rose-pink. One milliliter of 0.1 M EDTA corresponds to 0.04744 g of AlK(SO4)2 · 12H2O.
Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Use 20 g dissolved in 150 mL of hot water. Filter immediately.
Chloride [Part 2: Colorimetry and Turbidimetry; Chloride]. Use 2.0 g dissolved in warm water.
Ammonium Dissolve 1.0 g in 100 mL of ammonia-free water. To 20 mL of this solution, add 10% sodium hydroxide reagent solution until the precipitate first formed is redissolved. Dilute with water to 50 mL, and add 2 mL of Nessler reagent. Any color should not exceed that produced by 0.01 mg of ammonium ion (NH4) in an equal volume of solution containing the quantities of reagents used in the test.
Heavy Metals [Part 2: Colorimetry and Turbidimetry; Heavy Metals (as Lead); Procedure for Heavy Metals, Method 1]. Dissolve 5.0 g in 40 mL of water, and dilute with water to 50 mL. Use 30 mL to prepare the sample solution, and use 10 mL to prepare the control solution.
Iron [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. Use 1.0 g.
Sodium (By flame AAS, [Part 2: Trace and Ultratrace Elemental Analysis; Atomic Absorption Spectroscopy; Analysis; Procedure for Flame AAS]).
For the Determination of Sodium
S a m p l e S t o c k S o l u t i o n . Dissolve 1.0 g of sample in a 100 mL volumetric flask, and dilute to the mark with water (1 mL = 0.01 g).
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4011 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
For the Determination of Sodium
Element
Wavelength (nm)
Sample Wt (g)
Standard Added (mg)
Flame Type*
Background Correction
Na
589.0
0.05
0.01; 0.02
A/A
No
*A/A is air/acetylene.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4011 ACS Reagent Chemicals, Part 4
