Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Lithium Carbonate 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 Carbonate 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 in Dilute Hydrochloric Acid, Chloride, Nitrate, Sulfur Compounds, Heavy Metals, Iron, Calcium, Potassium, and Sodium.
Li2CO3
Formula Wt 73.89
CAS No. 554-13-2
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 matrix modifier melting point, 720 °C 0.7 g in 100 mL at 100 °C
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥99.0% Li2CO3 Maximum Allowable Insoluble in dilute hydrochloric acid . . . . . . . . 0.01% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.005% Nitrate (NO3) . . . . . . . . . . . . . . . . . . . . . . . 5 ppm Sulfur compounds (as SO4). . . . . . . . . . . . . . . 0.2% Heavy metals (by ICP–OES) . . . . . . . . . . . . . . 0.002% Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 0.002%
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4194 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Calcium (Ca) . . . . . . . . . . . . . . . . . . . . . . . 0.01% Potassium (K) . . . . . . . . . . . . . . . . . . . . . . . 0.01% Sodium (Na) . . . . . . . . . . . . . . . . . . . . . . . . 0.1%
TESTS Assay (By indirect acid–base titrimetry for carbonate). Weigh accurately about 1.3 g of sample, add 50 mL of water, and then add cautiously 50.0 mL of 1 N hydrochloric acid volumetric solution. Boil gently to expel carbon dioxide, cool, add 0.15 mL of methyl red indicator solution, and titrate the excess hydrochloric acid with 1 N sodium hydroxide volumetric solution. One milliliter of 1 N hydrochloric acid corresponds to 0.03694 g of Li2CO3.
Insoluble in Dilute Hydrochloric Acid Suspend 10 g in 75 mL of water, then add cautiously and slowly 25 mL of hydrochloric acid. Heat to boiling, and digest in a covered beaker on a hot plate (~100 °C) for 1 h. Filter through a tared, preconditioned filtering crucible, wash thoroughly with hot water, and dry at 105 °C.
Chloride [Part 2: Colorimetry and Turbidimetry; Chloride]. Dissolve 2.0 g in 25 mL of dilute nitric acid (1:5), dilute with water to 50 mL, and use 5.0 mL of this solution.
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 . Add 2.0 g to 4 mL of water in a test tube. Add brucine sulfate reagent solution, dropwise, until the sample is completely dissolved. Then dilute to 50 mL with the same reagent solution, and mix. C o n t r o l S o l u t i o n B . Add 2.0 g to 3 mL of water and 1 mL of nitrate ion (NO3) standard solution. Add brucine sulfate reagent solution, dropwise, until the sample is completely dissolved. Then dilute to 50 mL with the same reagent solution, and mix.
Continue with the procedure, starting with the preparation of blank solution C.
Sulfur Compounds Suspend 0.10 g in 10 mL of water, and cautiously neutralize with dilute hydrochloric acid (1:9). Add 0.10 mL of bromine water, and boil gently until the bromine is completely expelled. Add 2 mL of dilute hydrochloric acid (1:19), filter, and dilute with water to 40 mL. To 10 mL, add 1 mL of 12% barium chloride reagent solution. Any turbidity should not exceed that produced by 0.05 mg of sulfate ion (SO4) in an equal volume of solution containing 1 mL of dilute hydrochloric acid
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4194 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
(1:19) and 1 mL of 12% barium chloride reagent solution. Compare 10 min after adding the barium chloride to the sample and standard solutions.
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 0.5 g sample.
Iron [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. Suspend 0.5 g in 30 mL of water, cautiously add 3 mL of hydrochloric acid, and dilute with water to 50 mL. Use this solution without further acidification. Use only 2 mL of hydrochloric acid for the control solution.
Calcium, 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, Potassium, and Sodium
S a m p l e S t o c k S o l u t i o n . Suspend 5 g of sample in 50 mL of water, and cautiously add 25 mL of hydrochloric acid. Transfer the solution to a 100 mL volumetric flask, and dilute to the mark with water (1 mL = 0.05 g).
For the Determination of Calcium, Potassium, and Sodium
Element
Wavelength (nm)
Sample Wt (g)
Standard Added (mg)
Flame Type*
Background Correction
Ca
422.7
0.10
0.02; 0.04
N/A
No
K
766.5
1.0
0.05; 0.10
A/A
No
Na
589.0
0.01
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.4194 ACS Reagent Chemicals, Part 4
