Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Sodium Sulfate, Decahydrate 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 Sodium Sulfate, Decahydrate 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, pH of a 5% Solution at 25.0 °C, Insoluble Matter, Chloride, Phosphate, Heavy Metals, Iron, Calcium, Magnesium, and Potassium.
Na2SO4 • 10H2O
Formula Wt 322.19
CAS No. 7727-73-3
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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colorless solid Kjeldahl analysis melting point, 32 °C 36 g in 100 mL at 15 °C
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥99.0% Na2SO4 · 10H2O pH of a 5% solution at 25.0 °C . . . . . . . . . . . . 5.2–9.2 Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.01% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 5 ppm Phosphate (PO4) . . . . . . . . . . . . . . . . . . . . . 5 ppm Heavy metals (as Pb) . . . . . . . . . . . . . . . . . . 3 ppm Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 5 ppm Calcium (Ca) . . . . . . . . . . . . . . . . . . . . . . . 0.005% Magnesium (Mg) . . . . . . . . . . . . . . . . . . . . . 0.003% Potassium (K) . . . . . . . . . . . . . . . . . . . . . . . 0.005%
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4369 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Assay (By indirect acid–base titrimetry after ion exchange, [Part 2: Titrimetric Methods; Ion-Exchange Column Assays; Method for Ion-Exchange Column Assays]). Weigh accurately about 0.7 g of sample, and dissolve in about 50 mL of water. Pass the sample solution through the column at a rate of about 5 mL/min, collecting the eluate in a 500 mL titration flask. Wash the column with water at a rate of about 10 mL/min, collecting the washings in the same flask. Add 0.15 mL of phenolphthalein indicator solution, and titrate the eluate with 0.1 N sodium hydroxide. Continue to wash the column and to titrate the eluate until the passage of 50 mL of water requires no further titrant. One milliliter of 0.1 N sodium hydroxide corresponds to 0.01611 g of Na2SO4 · 10H2O.
pH of a 5% Solution at 25.0 °C [Part 2: Direct Electrometric Methods; pH Potentiometry; pH Range; Procedure for pH of a 5% Solution at 25.0 °C].
Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Use 10.0 g dissolved in 100 mL of water.
Chloride [Part 2: Colorimetry and Turbidimetry; Chloride]. Use 2.0 g.
Phosphate [Part 2: Colorimetry and Turbidimetry; Phosphate; Procedure for Phosphate, Method 1 (Direct Molybdenum Blue)]. Dissolve 4.0 g in 20 mL of 0.5 N sulfuric acid. For the standard, dilute 0.02 mg of phosphate ion (PO4) to 20 mL with 0.5 N sulfuric acid.
Heavy Metals [Part 2: Colorimetry and Turbidimetry; Heavy Metals (as Lead); Procedure for Heavy Metals, Method 1]. Dissolve 8.0 g in water, and dilute with water to 48 mL. Use 42 mL to prepare the sample solution, and use the remaining 6 mL to prepare the control solution.
Iron [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. Use 2.0 g.
Calcium, Magnesium, and Potassium (By flame AAS, [Part 2: Trace and Ultratrace Elemental Analysis; Atomic Absorption Spectroscopy; Analysis; Procedure for Flame AAS]).
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4369 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
For the Determination of Calcium, Magnesium, and Potassium
S a m p l e S t o c k S o l u t i o n . Dissolve 4.0 g in 50 mL of water in a 100 mL volumetric flask. Dilute to the mark with water (1 mL = 0.04 g).
For the Determination of Calcium, Magnesium, and Potassium
Element
Wavelength (nm)
Sample Wt (g)
Standard Added (mg)
Flame Type*
Background Correction
Ca
422.7
0.40
0.02; 0.04
N/A
No
Mg
285.2
0.40
0.01; 0.02
A/A
Yes
K
766.5
0.40
0.01; 0.02
A/A
No
*A/A is air/acetylene; N/A is nitrous oxide/acetylene.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4369 ACS Reagent Chemicals, Part 4
