Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Aluminum Sulfate, Hydrated 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 Sulfate, Hydrated 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, Calcium, Magnesium, Potassium, Sodium, Heavy Metals, and Iron.
Al2(SO4)3 · (1418)H2O
Formula Wt 666.40 (18H2O)
CAS No. 7784-31-8 (18H2O)
Note: This reagent is available in degrees of hydration ranging from 14 to 18 molecules of water.
GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . white solid Applications . . . . . . . . . . . . . . . . . . . . . . . . decolorizing, deodorizing, or precipitating agent; clarifying agent for fats and oils Change in state (approximate) . . . . . . . . . . . . melts when gradually heated Aqueous solubility . . . . . . . . . . . . . . . . . . . . miscible
SPECIFICATIONS Assay (as the labeled hydrate) . . . . . . . . . . . . 98.0–102.0%
Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.01% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.005%
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4012 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Calcium (Ca) . . . . . Magnesium (Mg) . . . Potassium (K) . . . . . Sodium (Na) . . . . . . Heavy metals (as Pb) Iron (Fe) . . . . . . . .
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0.01% 0.002% 0.005% 0.02% 0.001% 0.002%
TESTS Assay (By indirect complexometric titration of AlIII). Weigh accurately 8 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, mix, and then add 40.0 mL of standard 0.1 M EDTA 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 EDTAcorresponds to 0.02972 g of Al2(SO4)3 · 14H2O, 0.03152 g of Al2(SO4)3 · 16H2O, and 0.03332 g of Al2(SO4)3 · 18H2O.
where F = 29.72 for 14H2O, 31.52 for 16H2O, and 33.32 for 18H2O.
Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Use 20 g dissolved in 150 mL of water containing 5 mL of 25% sulfuric acid.
Chloride [Part 2: Colorimetry and Turbidimetry; Chloride]. Use 0.20 g.
Calcium, Magnesium, Potassium, and Sodium (By flame AAS, [Part 2: Trace and Ultratrace Elemental Analysis; Atomic Absorption Spectroscopy; Analysis; Procedure for Flame AAS]).
For the Determination of Calcium, Magnesium, Potassium, and Sodium
S a m p l e S t o c k S o l u t i o n . Dissolve 10.0 g of sample in 80 mL of water, add 2 mL of nitric acid (1:1), transfer to a 100 mL volumetric flask, dilute to the mark with water, and mix (1 mL = 0.10 g).
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4012 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
For the Determination of Calcium, Magnesium, Potassium, and Sodium
Element
Wavelength (nm)
Sample Wt (g)
Standard Added (mg)
Flame Type*
Background Correction
Ca
422.7
1.0
0.05; 0.10
N/A
No
Mg
285.2
1.0
0.01; 0.02
A/A
Yes
K
766.5
1.0
0.025; 0.05
A/A
No
Na
589.0
0.10
0.01; 0.02
A/A
No
*A/A is air/acetylene; N/A is nitrous oxide/acetylene.
Heavy Metals [Part 2: Colorimetry and Turbidimetry; Heavy Metals (as Lead); Procedure for Heavy Metals, Method 1]. Dissolve 4.0 g in 40 mL of water, and dilute with water to 48 mL. Use 36 mL to prepare the sample solution, and use the remaining 12 mL to prepare the control solution.
Iron [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. Dissolve 1.0 g in 40 mL of water; use 20 mL of this solution, and 1 mL of hydrochloric acid.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4012 ACS Reagent Chemicals, Part 4
