Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Zinc Sulfate Heptahydrate 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 Zinc Sulfate Heptahydrate 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, Nitrate, Ammonium, Calcium, Iron, Lead, Magnesium, Manganese, Potassium, and Sodium.
ZnSO4 • 7H2O
Formula Wt 287.54
CAS No. 7446-20-0
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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colorless or white solid preparation of complexometric titrant melting point, 40 °C; dehydrates completely at 200 °C 96 g in 100 mL at 20 °C
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99.0–103.0% ZnSO4 · 7H2O pH of a 5% solution at 25.0 °C . . . . . . . . . . . . 4.4–6.0 Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.01% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 5 ppm Nitrate (NO3) . . . . . . . . . . . . . . . . . . . . . . . 0.002% Ammonium (NH4) . . . . . . . . . . . . . . . . . . . . 0.001% Calcium (Ca) . . . . . . . . . . . . . . . . . . . . . . . 0.005% Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 0.001% Lead (Pb) . . . . . . . . . . . . . . . . . . . . . . . . . 0.003% Magnesium (Mg) . . . . . . . . . . . . . . . . . . . . . 0.005% Manganese (Mn) . . . . . . . . . . . . . . . . . . . . . 3 ppm
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4429 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Potassium (K) . . . . . . . . . . . . . . . . . . . . . . . 0.01% Sodium (Na) . . . . . . . . . . . . . . . . . . . . . . . . 0.05%
TESTS Assay (By complexometric determination of zinc). Weigh accurately about 1.0 g, transfer to a 500 mL beaker, and dissolve in about 300 mL of water. Add 15 mL of hexamethylenetetramine reagent solution and 50 mg of xylenol orange indicator mixture. Titrate with standard 0.1 M EDTA volumetric solution to a color change of purple-red to lemon yellow. One milliliter of 0.1 M EDTA corresponds to 0.02875 g of ZnSO4 · 7H2O.
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 10.0 g dissolved in 100 mL of water.
Chloride [Part 2: Colorimetry and Turbidimetry; Chloride]. Use 2.0 g.
Nitrate [Part 2: Colorimetry and Turbidimetry; Nitrate; Procedure for Nitrate, Method 1 (Brucine Sulfate)]. For sample solution A, use 1.0 g. After sample dissolution, add 2.0 mL of hydrochloric acid. For control solution B, after sample dissolution, add 2.0 mL of hydrochloric acid and 2.0 mL of nitrate ion (NO3) standard solution.
Ammonium Dissolve 1.0 g in 25 mL of water, pour into 25 mL of freshly boiled and cooled 10% sodium hydroxide reagent solution, 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 the quantities of reagents used in the test.
Calcium, Iron, Lead, Magnesium, Manganese, 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, Iron, Lead, Magnesium, Manganese, Potassium, and Sodium
S a m p l e S t o c k S o l u t i o n . Dissolve 10.0 g of sample in water in a 100 mL volumetric flask, add 0.5 mL of hydrochloric acid, and dilute with water to the mark (1 mL = 0.10 g).
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4429 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
For the Determination of Calcium, Iron, Lead, Magnesium, Manganese, Potassium, and Sodium
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
Fe
248.3
2.0
0.02; 0.04
A/A
Yes
Pb
217.0
2.0
0.06; 0.12
A/A
Yes
Mg
285.2
0.20
0.005; 0.01
A/A
Yes
Mn
279.5
2.0
0.005; 0.01
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
*A/A is air/acetylene; N/A is nitrous oxide/acetylene.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4429 ACS Reagent Chemicals, Part 4
