Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Magnesium Acetate Tetrahydrate 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 Magnesium Acetate Tetrahydrate 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, Sulfate, Barium, Chloride, Iron, Calcium, Manganese, Potassium, Sodium, Strontium, and Heavy Metals.
(CH3COO)2Mg • 4H2O
Formula Wt 214.45
CAS No. 16674-78-5
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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colorless, deliquescent solid buffer; detection of sodium melting point, 80 °C very soluble
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98.0–102.0% (CH3COO)2Mg · 4H2O Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.005% Sulfate (SO4) . . . . . . . . . . . . . . . . . . . . . . . 0.005% Barium (Ba) . . . . . . . . . . . . . . . . . . . . . . . . 0.001% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.001% Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 5 ppm Calcium (Ca) . . . . . . . . . . . . . . . . . . . . . . . 0.01% Manganese (Mn) . . . . . . . . . . . . . . . . . . . . . 0.001% Potassium (K) . . . . . . . . . . . . . . . . . . . . . . . 0.005% Sodium (Na) . . . . . . . . . . . . . . . . . . . . . . . . 0.005%
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4202 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Strontium (Sr) . . . . . . . . . . . . . . . . . . . . . . 0.005% Heavy metals (as Pb) . . . . . . . . . . . . . . . . . . 5 ppm
TESTS Assay (By complexometric titration of Mg). Weigh accurately about 0.85 g, and transfer to a 250 mL beaker with 50 mL of water. Add 5 mL of pH 10 ammoniacal buffer solution and about 50 mg of Eriochrome Black T indicator mixture. Titrate with 0.1 M EDTA volumetric solution to a clear blue color (and disappearance of the last trace of red). One milliliter of 0.1 M EDTA corresponds to 0.02145 g of (CH3COO)2Mg · 4H2O.
Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Use 20 g dissolved in 200 mL of dilute acetic acid (1:99). Retain the filtrate, without washings, for the test for sulfate.
Sulfate [Part 2: Colorimetry and Turbidimetry; Sulfate; Procedure for Sulfate, Method 1]. Use 1/20 of the filtrate from the test for insoluble matter. Allow 30 min for turbidity to form.
Barium Dissolve 6.0 g in 25 mL of dilute nitric acid (1:1). For the control, dissolve 1.0 g in 25 mL of dilute nitric acid (1:1), and add 0.05 mg of barium. Evaporate each solution on a hot plate (~100 °C) to a syrupy consistency, and add 20 mL of water. If the solutions are not clear, add 10% nitric acid until clear. Add 1 mL of 1 N acetic acid and 2 mL of potassium dichromate reagent solution to each, and adjust the pH to 7 (using a pH meter) with 10% ammonium hydroxide reagent solution. Add 25 mL of methanol to each, and stir vigorously. Any turbidity in the solution of the sample should not exceed that in the control.
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For the Determination of Chloride and Iron
S a m p l e S o l u t i o n A . Dissolve 10 g in water, filter if necessary through a chloride-free filter, and dilute with water to 100 mL (1 mL = 0.10 g).
Chloride† [Part 2: Colorimetry and Turbidimetry; Chloride]. Use 10 mL of sample solution A (1 g sample).
Iron† [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. Use 20 mL of sample solution A (2.0 g sample).
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4202 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Calcium, Manganese, Potassium, Sodium, and Strontium (By flame AAS, [Part 2: Trace and Ultratrace Elemental Analysis; Atomic Absorption Spectroscopy; Analysis; Procedure for Flame AAS]).
For the Determination of Calcium, Manganese, Potassium, Sodium, and Strontium
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 75 mL of water, transfer to a 100 mL volumetric flask, and dilute to the mark with water (1 mL = 0.10 g).
For the Determination of Calcium, Manganese, Potassium, Sodium, and Strontium
Element
Wavelength (nm)
Sample Wt (g)
Standard Added (mg)
Flame Type*
Background Correction
Ca
422.7
0.20
0.02; 0.04
N/A
No
Mn
279.5
2.0
0.02; 0.04
A/A
Yes
K
766.5
1.0
0.05; 0.10
A/A
No
Na
589.0
0.20
0.01; 0.02
A/A
No
Sr
460.7
1.0
0.05; 0.10
N/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 6.0 g in 20 mL of water, and dilute with water to 30 mL. Use 25 mL to prepare the sample solution, and use the remaining 5.0 mL to prepare the control solution.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4202 ACS Reagent Chemicals, Part 4
