Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Potassium Acetate 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 Potassium Acetate 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, pH of a 5% Solution at 25.0 °C, Insoluble Matter, Chloride, Phosphate, Sulfate, Heavy Metals, Iron, Calcium, Magnesium, and Sodium.
CH3COOK
Formula Wt 98.14
CAS No. 127-08-2
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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white or colorless solid buffers melting point, 290 °C 253 g in 100 mL at 20 °C
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥99.0% CH3COOK pH of a 5% solution at 25.0 °C . . . . . . . . . . . . 6.5–9.0 Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.005% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.003% Phosphate (PO4) . . . . . . . . . . . . . . . . . . . . . 0.001% Sulfate (SO4) . . . . . . . . . . . . . . . . . . . . . . . 0.002% Heavy metals (by ICP–OES) . . . . . . . . . . . . . . 5 ppm Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 5 ppm Calcium (Ca) . . . . . . . . . . . . . . . . . . . . . . . 0.005% Magnesium (Mg) . . . . . . . . . . . . . . . . . . . . . 0.002% Sodium (Na) . . . . . . . . . . . . . . . . . . . . . . . . 0.03%
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4274 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Assay (By nonaqueous acid–base titrimetry). Weigh, to the nearest 0.1 mg, about 0.4 g, and dissolve in 5 mL of acetic anhydride and 25 mL of acetic acid. Add 0.15 mL of crystal violet indicator solution, and titrate in a closed system with 0.1 N perchloric acid in glacial acetic acid volumetric solution to a green end point. Perform a blank determination, and make any necessary correction. One milliliter of 0.1 N perchloric acid corresponds to 0.00981 g of CH3COOK.
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]. Use 20 g dissolved in 200 mL of water.
Chloride [Part 2: Colorimetry and Turbidimetry; Chloride]. Use 0.33 g.
Phosphate [Part 2: Colorimetry and Turbidimetry; Phosphate; Procedure for Phosphate, Method 2 (Extracted Molybdenum Blue)]. Dissolve 1.0 g in 10 mL of sulfuric acid, and evaporate to near dryness on a hot plate (~100 °C). Gently heat with a burner until the salt is dry. Add 10 mL of sulfuric acid, and repeat the evaporation and drying. Dissolve in 80 mL of water, add 0.5 g of ammonium molybdate, and adjust the pH to 1.8 (using a pH meter) with dilute hydrochloric acid (1:9). Heat to boiling, cool, add 10 mL of hydrochloric acid, and proceed as described. Carry along a standard containing 0.01 mg of phosphate ion (PO4) treated in the same manner as the sample after the addition of 80 mL of water.
Sulfate [Part 2: Colorimetry and Turbidimetry; Sulfate; Procedure for Sulfate, Method 1].
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 2.0 g.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4274 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Calcium, Magnesium, 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, Magnesium, and Sodium
S a m p l e S t o c k S o l u t i o n . Dissolve 5.0 g of sample in 80 mL of water. Transfer to a 100 mL volumetric flask, and dilute to the mark with water (1 mL = 0.05 g).
For the Determination of Calcium, Magnesium, and Sodium
Element
Wavelength (nm)
Sample Wt (g)
Standard Added (mg)
Flame Type*
Background Correction
Ca
422.7
0.50
0.025; 0.05
N/A
No
Mg
285.2
0.50
0.01; 0.02
A/A
Yes
Na
589.0
0.03
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.4274 ACS Reagent Chemicals, Part 4
