Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Magnesium Chloride Hexahydrate 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
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ABSTRACT This monograph for Magnesium Chloride Hexahydrate 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, Nitrate, Phosphate, Sulfate, Ammonium, Barium, Calcium, Manganese, Potassium, Sodium, Strontium, Heavy Metals, and Iron.
MgCl2 • 6H2O
Formula Wt 203.30
CAS No. 7791-18-6
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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colorless, deliquescent solid adjustment of ion strength melting point, 115 °C, with decomposition 167 g in 100 mL
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99.0–102.0% MgCl2 · 6H2O Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.005% Nitrate (NO3) . . . . . . . . . . . . . . . . . . . . . . . 0.001% Phosphate (PO4) . . . . . . . . . . . . . . . . . . . . . 5 ppm Sulfate (SO4) . . . . . . . . . . . . . . . . . . . . . . . 0.002% Ammonium (NH4) . . . . . . . . . . . . . . . . . . . . 0.002% Barium (Ba) . . . . . . . . . . . . . . . . . . . . . . . . 0.005% Calcium (Ca) . . . . . . . . . . . . . . . . . . . . . . . 0.01% Manganese (Mn) . . . . . . . . . . . . . . . . . . . . . 5 ppm Potassium (K) . . . . . . . . . . . . . . . . . . . . . . . 0.005% Sodium (Na) . . . . . . . . . . . . . . . . . . . . . . . . 0.005%
© 2017 American Chemical Society
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ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4203 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Strontium (Sr) . . . . . . . . . . . . . . . . . . . . . . 0.005% Heavy metals (by ICP–OES) . . . . . . . . . . . . . . 5 ppm Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 5 ppm
TESTS Assay
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(By complexometric titration of Mg). Weigh accurately about 0.8 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 0.02033 g of MgCl2 · 6H2O.
Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Use 20 g dissolved in 200 mL of water.
Nitrate [Part 2: Colorimetry and Turbidimetry; Nitrate; Procedure for Nitrate, Method 1 (Brucine Sulfate)].
For the Determination of Nitrate
S a m p l e S o l u t i o n A . Dissolve 1.0 g in 3 mL of water by heating in a boiling water bath. Dilute to 50 mL with brucine sulfate reagent solution. C o n t r o l S o l u t i o n B . Dissolve 1.0 g in 2 mL of water and 1 mL of nitrate ion (NO3) standard solution by heating in a boiling water bath. Dilute to 50 mL with brucine sulfate reagent solution.
Continue with the procedure, starting with the preparation of blank solution C.
Phosphate [Part 2: Colorimetry and Turbidimetry; Phosphate; Procedure for Phosphate, Method 1 (Direct Molybdenum Blue)]. Dissolve 4.0 g in 25 mL of approximately 0.5 N sulfuric acid, and continue as described.
Sulfate [Part 2: Colorimetry and Turbidimetry; Sulfate; Procedure for Sulfate, Method 1]. Use 2.5 g of sample.
Ammonium Dissolve 1.0 g in 90 mL of water and add 10 mL of freshly boiled 10% sodium hydroxide reagent solution. Allow to settle, decant 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 5 mL of 10% sodium hydroxide reagent solution and 2 mL of Nessler reagent.
© 2017 American Chemical Society
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ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4203 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Barium Dissolve 1.5 g in 20 mL of water. For the control, dissolve 0.5 g in 15 mL of water, add 0.05 mg of barium ion (Ba), and dilute with water to 20 mL. To each solution, add 1 mL of 1 N acetic acid and 2 mL of potassium dichromate reagent solution. Adjust the pH of the control and sample solutions to 7 (using a pH meter) with 10% ammonium hydroxide reagent solution, add 25 mL of methanol, and stir vigorously. Any turbidity in the solution of the sample should not exceed that in the control.
Calcium, Manganese, Potassium, Sodium, and Strontium (By flame AAS, [Part 2: Trace and Ultratrace Elemental Analysis; Atomic Absorption Spectroscopy; Analysis; Procedure for Flame AAS]).
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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 with water in 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
0.01; 0.02
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: Trace and Ultratrace Elemental Analysis; Inductively Coupled Plasma−Optical Emission Spectroscopy (ICP–OES); Calculation of Heavy Metals (by ICP–OES) Results], by ICP–OES). Use 2.0 g sample.
Iron [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. Use 2.0 g.
© 2017 American Chemical Society
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ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4203 ACS Reagent Chemicals, Part 4
