Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Cobalt Chloride Hexahydrate (Cobalt(II) Chloride Hexahydrate; Cobaltous Chloride Hexahydrate) 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 Cobalt Chloride Hexahydrate 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 Matter, Nitrate, Sulfate, Calcium, Copper, Iron, Magnesium, Nickel, Potassium, Sodium, and Zinc.
CoCl2·6H2O
Formula Wt 237.93
CAS No. 7791-13-1
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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pink to red solid APHA color standard melting point, 86 °C 93 g in 100 mL at 20 °C
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98.0–102.0% CoCl2 · 6H2O Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.01% Nitrate (NO3) . . . . . . . . . . . . . . . . . . . . . . . 01% Sulfate (SO4) . . . . . . . . . . . . . . . . . . . . . . . 0.01% Calcium (Ca) . . . . . . . . . . . . . . . . . . . . . . . 0.005% Copper (Cu) . . . . . . . . . . . . . . . . . . . . . . . . 0.002% Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 0.005% Magnesium (Mg) . . . . . . . . . . . . . . . . . . . . . 0.005% Nickel (Ni) . . . . . . . . . . . . . . . . . . . . . . . . . 0.1% Potassium (K) . . . . . . . . . . . . . . . . . . . . . . . 0.01%
© 2017 American Chemical Society
A
DOI:10.1021/acsreagents.4098 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Sodium (Na) . . . . . . . . . . . . . . . . . . . . . . . . 0.05% Zinc (Zn) . . . . . . . . . . . . . . . . . . . . . . . . . . 0.03%
TESTS Assay (By complexometric titration of cobalt). Weigh, to the nearest 0.1 mg, 1.0 g of sample, and dissolve in 200 mL of water. Add about 0.2 g of ascorbic acid and 5 g of ammonium acetate, followed by 10 mL of ammonium hydroxide. Add about 0.1 g of murexide indicator mixture, and titrate with 0.1 M EDTA volumetric solution to the violet end point. The color change must persist for 30 s. One milliliter of 0.1 M EDTA corresponds to 0.02379 g of CoCl2 · 6H2O.
Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Use 10.0 g dissolved in 100 mL of water.
Nitrate [Part 2: Colorimetry and Turbidimetry; Nitrate; Procedure for Nitrate, Method 1 (Brucine Sulfate)]. Dissolve 1.0 g in 10 mL of water. Add this solution in small portions and with constant stirring to 10 mL of 10% sodium hydroxide reagent solution. Digest in a covered beaker on a hot plate (~100 °C) for 15 min. Cool, dilute with water to 20 mL, and filter.
For the Determination of Nitrate
S a m p l e S o l u t i o n A . To 4 mL of the preceding filtrate, add 6 mL of water. 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 . To 4 mL of the preceding filtrate, add 4 mL of water and 2 mL of nitrate ion (NO3) standard solution. Dilute to 50 mL with brucine sulfate reagent solution.
Continue with the procedure, starting with preparation of blank solution C.
Sulfate [Part 2: Colorimetry and Turbidimetry; Sulfate; Procedure for Sulfate, Method 1]. Use 1/20 of the filtrate from the test for insoluble matter. Allow 30 min for turbidity to develop.
Calcium, Copper, Iron, Magnesium, Nickel, Potassium, Sodium, and Zinc (By flame AAS, [Part 2: Trace and Ultratrace Elemental Analysis; Atomic Absorption Spectroscopy; Analysis; Procedure for Flame AAS]).
© 2017 American Chemical Society
B
DOI:10.1021/acsreagents.4098 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
For the Determination of Calcium, Copper, Iron, Magnesium, Nickel, Potassium, Sodium, and Zinc
S a m p l e S t o c k S o l u t i o n . Dissolve 20.0 g of sample in water, add 2 mL of nitric acid, and dilute to the mark with water in a 200 mL volumetric flask (1 mL = 0.10 g).
For the Determination of Calcium, Copper, Iron, Magnesium, Nickel, Potassium, Sodium, and Zinc
Element
Wavelength (nm)
Sample Wt (g)
Standard Added (mg)
Flame Type*
Background Correction
Ca
422.7
0.80
0.02; 0.04
N/A
No
Cu
324.8
2.0
0.04; 0.08
A/A
Yes
Fe
248.3
2.0
0.05; 0.10
A/A
Yes
Mg
285.2
0.20
0.005; 0.01
A/A
Yes
Ni
232.0
0.10
0.05; 0.10
A/A
Yes
K
766.5
0.20
0.01; 0.02
A/A
No
Na
589.0
0.04
0.01; 0.02
A/A
No
Zn
213.9
0.10
0.01; 0.02
A/A
Yes
*A/A is air/acetylene; N/A is nitrous oxide/acetylene.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4098 ACS Reagent Chemicals, Part 4
