Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Lithium Sulfate Monohydrate 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 Lithium Sulfate Monohydrate 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, Loss on Drying, Insoluble Matter, Chloride, Nitrate, Heavy Metals, Iron, Potassium and Sodium.
Li2SO4 • H2
Formula Wt 127.95
CAS No. 10102-25-7
Note: The formula weight of this reagent is likely to deviate from the value cited because the natural distribution of 6 Li and 7Li isotopes is often altered in current sources of lithium compounds.
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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white solid preparation of lithium standard solutions dehydrates at 130 °C; anhydrous melts at 860 °C 35 g in 100 mL at 25 °C
SPECIFICATIONS Assay (dried basis). . . . . . . . . . . . . . . . . . . . ≥99.0% Li2SO4 Loss on drying . . . . . . . . . . . . . . . . . . . . . . 13.0–15.0% Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.01% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.002% Nitrate (NO3) . . . . . . . . . . . . . . . . . . . . . . . 0.001% Heavy metals (as Pb) . . . . . . . . . . . . . . . . . . 0.001% Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 0.001%
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4199 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Potassium (K) . . . . . . . . . . . . . . . . . . . . . . . 0.05% Sodium (Na) . . . . . . . . . . . . . . . . . . . . . . . . 0.05%
TESTS Assay (By indirect acid–base titrimetry). Weigh, to the nearest 0.1 mg, 0.3 g of previously dried sample (see loss on drying test), and dissolve in 50 mL of water. Pass the solution through a cation-exchange column [Part 2: Titrimetric Methods; IonExchange Column Assays; Method for Ion-Exchange Column Assays] at the rate of about 5 mL/min, and collect the eluate in a 500 mL titration flask. Then wash the resin in the column with water at a rate of about 10 mL/min, and collect in the same titration flask. Add 0.15 mL of phenolphthalein indicator solution to the flask, and titrate with 0.1 N sodium hydroxide. Continue the titration, as the washing proceeds, until 50 mL of eluate requires no further titration. One milliliter of 0.1 N sodium hydroxide corresponds to 0.05497 g of Li2SO4.
Loss on Drying Weigh accurately about 1 g, and dry at 150 °C to constant weight. (The theoretical loss for Li2SO4 · H2O is 14.08%.) Save the dried sample for the assay.
Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Use 10 g dissolved in 100 mL of water.
Chloride [Part 2: Colorimetry and Turbidimetry; Chloride]. Use 0.50 g.
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 5 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 4 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.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4199 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
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. Use 30 mL to prepare the sample solution, and use the remaining 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.
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 Potassium and 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 with water in a 100 mL volumetric flask, and dilute to the mark with water (1 mL = 0.01 g).
For the Determination of Potassium and Sodium
Element
Wavelength (nm)
Sample Wt (g)
Standard Added (mg)
Flame Type*
Background Correction
K
766.5
0.10
0.05; 0.10
A/A
No
Na
589.0
0.02
0.01; 0.02
A/A
No
*A/A is air/acetylene.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4199 ACS Reagent Chemicals, Part 4
