Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Calcium Chloride Dihydrate 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 Chloride Dihydrate provides, in addition to common physical constants, a general description including typical appearance, applications, 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, Oxidizing Substances, Sulfate, Ammonium, Barium, Heavy Metals, Iron, Magnesium, Potassium, Sodium, and Strontium.
CaCl2·2H2O
Formula Wt 147.01
CAS No. 10035-04-8
GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . colorless or white hygroscopic solid Applications . . . . . . . . . . . . . . . . . . . . . . . . preparation of calcium standard solutions; electrolyte Aqueous solubility . . . . . . . . . . . . . . . . . . . . 326 g in 100 mL at 60 °C
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99.0–105.0% CaCl2 · 2H2O pH of a 5% solution at 25.0 °C . . . . . . . . . . . . 4.5–8.5 Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.01% Oxidizing substances (as NO3). . . . . . . . . . . . . 0.003% Sulfate (SO4) . . . . . . . . . . . . . . . . . . . . . . . 0.01% Ammonium (NH4) . . . . . . . . . . . . . . . . . . . . 0.005% Barium (Ba) . . . . . . . . . . . . . . . . . . . . . . . . 0.005% Heavy metals (by ICP–OES) . . . . . . . . . . . . . . 5 ppm Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 0.001% Magnesium (Mg) . . . . . . . . . . . . . . . . . . . . . 0.005% Potassium (K) . . . . . . . . . . . . . . . . . . . . . . . 0.01%
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4080 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Sodium (Na) . . . . . . . . . . . . . . . . . . . . . . . . 0.02% Strontium (Sr) . . . . . . . . . . . . . . . . . . . . . . 0.1%
TESTS Assay (By complexometric titration of calcium). Weigh accurately about 2.5 g in a 250 mL beaker. Dissolve in 100 mL of water, and add 5 mL of 10% hydrochloric acid. Transfer to a 250 mL volumetric flask, dilute to the mark with water, and mix. Pipette 50.0 mL of the sample solution to a 400 mL beaker, add 75 mL of water, and while stirring add 20 mL of 0.1 M EDTA from a 50 mL burette. Adjust the pH using a pH meter to above 12 with 10% sodium hydroxide reagent solution. Add 300 mg of hydroxynaphthol blue indicator mixture, and continue the titration immediately with 0.1 M EDTA volumetric solution to a blue color. One milliliter of 0.1 M EDTA corresponds to 0.014701 g of CaCl2 · 2H2O.
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]. Dissolve 20 g in 200 mL of water.
Oxidizing Substances Place 0.20 g in a beaker. Cool the beaker thoroughly in an ice bath, and add 22 mL of sulfuric acid that has been cooled to ice-bath temperature. Allow the mixture to warm to room temperature, and swirl the beaker at intervals to effect gentle dissolution with slow evolution of hydrogen chloride. When dissolution is complete, add 3 mL of diphenylamine reagent solution and digest on a hot plate (~100 °C) for 90 min. Prepare a standard by evaporating to dryness a solution containing 0.006 mg of nitrate (0.6 mL of the nitrate standard solution) and 0.01 g of sodium carbonate. Treat the residue exactly like the sample. Any color produced in the solution of the sample should not exceed that in the standard.
Sulfate Dissolve 1.0 g of sample in 20 mL of water, and add 1.0 mL of 10% hydrochloric acid. Filter through a small, washed filter paper. Add two 3 mL portions of water through the filter paper. For the control, take 0.10 mg of sulfate ion (SO4) in 25 mL of water, and add 1.0 mL of 10% hydrochloric acid. Dilute both solutions to 35 mL with water, and add 1 mL of 12% barium chloride solution. Compare turbidity after 10 min. Sample turbidity should not exceed that of the control solution.
†
For the Determination of Ammonium, Barium, Heavy Metals, and Iron
S a m p l e S o l u t i o n A . Dissolve 50 g in about 200 mL of water, filter if necessary, and dilute with water to 250 mL in a volumetric flask (1 mL = 0.2 g).
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4080 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Ammonium
†
Dilute 10 mL (2 g sample) of sample solution A to 45 mL, and add 15 mL of 10% sodium hydroxide reagent solution. Filter through a filtering crucible previously washed with 10% sodium hydroxide reagent solution. Dilute 6 mL of the filtrate to 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 1.5 mL of 10% sodium hydroxide reagent solution and 2 mL of Nessler reagent. B a r i u m . For the sample, add 2 g of sodium acetate and 0.05 mL of glacial acetic acid to 15 mL (3 g sample) of sample solution A. For the control, add 2 g of sodium acetate, 0.05 mL of glacial acetic acid, and 0.1 mg of barium ion to 5 mL (1 g sample) of sample solution A, and dilute with water to 15 mL. To each solution, add 2 mL of 10% potassium dichromate reagent solution, and allow to stand for 15 min. Any turbidity in the solution of the sample should not exceed that in the control.
Barium† For the sample, add 2 g of sodium acetate and 0.05 mL of glacial acetic acid to 15 mL (3 g sample) of sample solution A. For the control, add 2 g of sodium acetate, 0.05 mL of glacial acetic acid, and 0.1 mg of barium ion to 5 mL (1 g sample) of sample solution A, and dilute with water to 15 mL. To each solution, add 2 mL of 10% potassium dichromate reagent solution, and allow to stand for 15 min. Any turbidity in the solution of the sample should not exceed that in the control.
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 5.0 mL (1 g sample) of sample solution A.
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 Magnesium, Potassium, Sodium, and Strontium
S a m p l e S t o c k S o l u t i o n . Dissolve 2.0 g of sample in 50 mL of water and 5 mL of nitric acid in a 200 mL volumetric flask, and dilute to the mark with water (1 mL = 0.01 g).
For the Determination of Magnesium, Potassium, Sodium, and Strontium
Element
Wavelength (nm)
Sample Wt (g)
Standard Added (mg)
Flame Type*
Background Correction
Mg
285.2
0.20
0.01; 0.02
A/A
Yes
K
766.5
0.20
0.02; 0.04
A/A
No
Na
589.0
0.05
0.01; 0.02
A/A
No
Sr
460.7
0.05
0.05; 0.10
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.4080 ACS Reagent Chemicals, Part 4
