Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Calcium 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 Calcium 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, Fluoride, Sulfate, Ammonium, Heavy Metals, Iron, Barium, Magnesium, Potassium, Sodium, and Strontium.
CaCO3
Formula Wt 100.09
CAS No. 471-34-1
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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white solid determining halogens in organic compounds decomposes, 825 °C insoluble
SPECIFICATIONS Assay (dried basis). . . . . . . . . . . . . . . . . . . . ≥99.0% CaCO3 Maximum Allowable Insoluble in dilute hydrochloric acid . . . . . . . . 0.01% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.001% Fluoride (F) . . . . . . . . . . . . . . . . . . . . . . . . 0.0015% Sulfate (SO4) . . . . . . . . . . . . . . . . . . . . . . . 0.01% Ammonium (NH4) . . . . . . . . . . . . . . . . . . . . 0.003% Heavy metals (by ICP–OES) . . . . . . . . . . . . . . 0.001% Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 0.003% Barium (Ba) . . . . . . . . . . . . . . . . . . . . . . . . 0.01% Magnesium (Mg) . . . . . . . . . . . . . . . . . . . . . 0.02% Potassium (K) . . . . . . . . . . . . . . . . . . . . . . . 0.01%
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4076 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Sodium (Na) . . . . . . . . . . . . . . . . . . . . . . . . 0.1% Strontium (Sr) . . . . . . . . . . . . . . . . . . . . . . 0.1%
TESTS Assay (By complexometric titration of calcium). Weigh accurately about 0.4 g, previously dried at 300 °C for 4 h, and transfer to a 400 mL beaker. Cover the beaker with a watch glass. Add 2 mL of 20% hydrochloric acid from a pipette placed between the lip of the beaker and the watch glass. Swirl the beaker to aid dissolution. With water, wash down the inner wall of the beaker, the outer surface of the pipette, and the watch glass. Dilute to about 100 mL with water. While stirring, add from a 50 mL burette about 30 mL of 0.1 M EDTA volumetric solution. Adjust the solution to above pH 12 (using a pH meter with a suitable high-pH glass electrode) with 10% sodium hydroxide reagent solution. Add 300 mg of hydroxynaphthol blue indicator mixture, and continue the titration immediately with 0.1 M EDTA to a blue color. One milliliter of 0.1 M EDTA corresponds to 0.01001 g of CaCO3.
Insoluble in Dilute Hydrochloric Acid Add 10 g to about 100 mL of water, swirl, slowly and carefully add 20 mL of hydrochloric acid, and dilute with water to 150 mL. Heat the solution to boiling, boil gently to expel the carbon dioxide, and digest in a covered beaker on a hot plate (~100 °C) for 1 h. Filter through a tared filtering crucible, wash thoroughly, and dry at 105 °C.
Chloride [Part 2: Colorimetry and Turbidimetry; Chloride]. Dissolve 1.0 g in 10 mL of water plus 2 mL of nitric acid, filter if necessary through a small chloride-free filter, wash with hot water, and dilute with water to 20 mL.
Fluoride Dissolve 1.0 g in 50 mL of water and 20 mL of 1 N hydrochloric acid in a 250 mL beaker. For the standards, add 1.0, 2.0, 3.0, 5.0, 10.0, and 15.0 mL of fluoride ion (F) standard solution to 250 mL glass beakers containing 50 mL of water and 5 mL of 1 N hydrochloric acid. Boil the sample and six standard solutions for a few seconds, cool rapidly, and transfer to plastic beakers. To each solution, add 10 mL of 1 M sodium citrate reagent solution and 10 mL of 0.2 M (ethylenedinitrilo)tetraacetate, disodium salt, reagent solution, and mix. If necessary, adjust the pH to 5.5 ± 0.1 with dilute hydrochloric acid (1:9) or dilute sodium hydroxide (1:9). Transfer to 100 mL volumetric flasks, dilute to the mark with water, mix, and pour into plastic beakers. For each solution, measure immediately the potential of a fluoride electrode versus a reference electrode using a pH meter with an expanded scale or an appropriate potentiometer. Plot a 2-cycle semilogarithmic calibration curve with micrograms of fluoride per 100 mL of solution on the logarithmic scale. Determine the concentration of fluoride from the calibration curve.
Sulfate Cautiously dissolve 1.0 g of sample with 10 mL of dilute hydrochloric acid (1:1) in a 100 mL beaker. Add 0.05 mL of bromine water, and evaporate to dryness. Dissolve the residue in 5 mL of water, and evaporate to dryness. Dissolve the residue in 15 mL of water, add 1 mL of dilute hydrochloric acid (1:19), and filter through a small, washed filter paper. Add two 3 mL portions of water to the same filter. For the control, take 0.10 mg of sulfate ion (SO4) in 15 mL of water, and add 1 mL of dilute hydrochloric acid (1:19). Dilute both solutions to 25 mL, add 1 mL of 12% barium chloride reagent solution, and mix. Compare after 10 min. Sample turbidity should not exceed that of the control solution.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4076 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
†
For the Determination of Ammonium, Heavy Metals, and Iron
S a m p l e S o l u t i o n A . In a 400 mL beaker, cautiously dissolve 20 g in 100 mL of dilute hydrochloric acid (1:1), and evaporate on a hot plate (~100 °C) to dryness or a moist residue. Dissolve the residue in about 100 mL of water, filter, and dilute with water to 200 mL (1 mL = 0.1 g).
Ammonium† Dilute 10 mL (1 g sample) of sample solution A with water to 80 mL, add 20 mL of 10% sodium hydroxide reagent solution, stopper, mix well, and allow to stand for 1 h. Decant 50 mL through a filtering crucible that has been washed with 10% sodium hydroxide reagent solution, and add to the filtrate 2 mL of Nessler reagent. Any color should not exceed that produced by 0.015 mg of ammonium ion (NH4) in an equal volume of solution containing the quantities of reagents used in the test.
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 1.0 g sample.
Iron† [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. Use 3.3 mL of sample solution A (0.33 g sample).
Barium, Magnesium, 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 Barium, Magnesium, Potassium, Sodium, and Strontium
S a m p l e S t o c k S o l u t i o n B . Cautiously dissolve 10.0 g of sample in 50 mL of nitric acid (1:3), transfer to a 100 mL volumetric flask, and dilute to the mark with water (1 mL = 0.10 g). S a m p l e S t o c k S o l u t i o n C . Transfer 5.0 mL (0.50 g) of sample stock solution B to a 100 mL volumetric flask, and dilute to the mark with water (1 mL = 0.005 g).
For the Determination of Barium, Magnesium, Potassium, Sodium, and Strontium
Element
Wavelength (nm)
Sample Wt (g)
Standard Added (mg)
Flame Type*
Background Correction
Ba
553.6
2.0
0.10; 0.20
N/A
No
Mg
285.2
0.10
0.01; 0.02
A/A
Yes
K
766.5
0.50
0.05; 0.10
A/A
No
Na
589.0
0.01
0.01; 0.02
A/A
No
Sr
460.7
0.10
0.10; 0.20
N/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.4076 ACS Reagent Chemicals, Part 4
