Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Ferric Ammonium Sulfate Dodecahydrate (Ammonium Iron(III) Sulfate Dodecahydrate; Ammonium Ferric Sulfate Dodecahydrate) 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 Ferric Ammonium Sulfate Dodecahydrate 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, Chloride, Nitrate, Calcium, Copper, Magnesium, Potassium, Sodium, Zinc, and Ferrous Iron.
Fe(SO4)2 NH4· 12H2O
Formula Wt 482.18
CAS No. 7783-83-7
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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violet solid indicator for argentimetric titrations melting point, 37 °C soluble
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98.5–102.0% Fe(SO4)2NH4 · 12(H2O) Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.01% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.001% Nitrate (NO3) . . . . . . . . . . . . . . . . . . . . . . . 0.01% Calcium (Ca) . . . . . . . . . . . . . . . . . . . . . . . 0.01% Copper (Cu) . . . . . . . . . . . . . . . . . . . . . . . . 0.003% Magnesium (Mg) . . . . . . . . . . . . . . . . . . . . . 0.005% Potassium (K) . . . . . . . . . . . . . . . . . . . . . . . 0.005% Sodium (Na) . . . . . . . . . . . . . . . . . . . . . . . . 0.02%
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4142 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Zinc (Zn) . . . . . . . . . . . . . . . . . . . . . . . . . . 0.003% Ferrous iron (Fe++). . . . . . . . . . . . . . . . . . . . Passes test
TESTS Assay (By iodometric titration of oxidative capacity of FeIII). Weigh accurately about 1.8 g and transfer to an iodine flask with 50 mL of water. Add 3 mL of hydrochloric acid and 3.0 g of potassium iodide. Stopper, swirl, and allow to stand in the dark for 30 min. Dilute with 100 mL of water and titrate the liberated iodine with 0.1 N sodium thiosulfate volumetric solution, adding 3 mL of starch indicator solution near the end of the titration. Correct for a blank. One milliliter of 0.1 N sodium thiosulfate corresponds to 0.04822 g of Fe(SO4)2NH4 · 12H2O.
Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Use 10.0 g of sample dissolved in 100 mL of dilute hydrochloric acid (1:99).
Chloride Dissolve 4.0 g in 40 mL of dilute nitric acid (1:9), filter if necessary through a chloride-free filter, and dilute with water to 60 mL. For the sample, use 30 mL of the solution. For the control, add 0.01 mg of chloride ion (Cl) and 1 mL of nitric acid to 15 mL of the solution, and dilute with water to 30 mL. To each solution, add 1 mL of silver nitrate reagent solution. Any turbidity in the solution of the sample should not exceed that in the control.
Nitrate [Part 2: Colorimetry and Turbidimetry; Nitrate; Procedure for Nitrate, Method 1 (Brucine Sulfate)]. Dissolve 2.0 g in 1 mL of water by swirling in a test tube. Add 10 mL of dilute ammonium hydroxide (1:1), mix well, and filter through a dry filter paper. Do not wash the precipitate.
For the Determination of Nitrate
S a m p l e S o l u t i o n A . Add 1.0 mL of the filtrate to 2 mL of water, dilute to 50 mL with brucine sulfate reagent solution, and mix. C o n t r o l S o l u t i o n B . Add 1.0 mL of the filtrate to 2 mL of the nitrate ion (NO3) standard solution, dilute to 50 mL with brucine sulfate reagent solution, and mix.
Continue with the procedure, starting with the preparation of blank solution C.
Calcium, Copper, Magnesium, 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
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DOI:10.1021/acsreagents.4142 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
For the Determination of Calcium, Copper, Magnesium, Potassium, Sodium, and Zinc
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 90 mL of nitric acid (1:19) in a 100 mL volumetric flask, and dilute to the mark with water (1 mL = 0.10 g).
For the Determination of Calcium, Copper, Magnesium, Potassium, Sodium, and Zinc
Element
Wavelength (nm)
Sample Wt (g)
Standard Added (mg)
Flame Type*
Background Correction
Ca
422.7
1.00
0.05; 0.10
N/A
No
Cu
324.7
1.0
0.03; 0.06
A/A
Yes
Mg
285.2
0.10
0.005; 0.01
A/A
Yes
K
766.5
1.00
0.025; 0.05
A/A
No
Na
589.0
0.10
0.01; 0.02
A/A
No
Zn
213.9
0.20
0.005; 0.01
A/A
Yes
*A/A is air/acetylene; N/A is nitrous oxide/acetylene.
Ferrous Iron Dissolve 1.0 g in a mixture of 20 mL of water and 1 mL of hydrochloric acid, and add 0.05 mL of a freshly prepared 5% potassium ferricyanide reagent solution in a 25 mL glass-stoppered flask. Stopper immediately. No blue or green color should be produced in 1 min. (Limit about 0.001%.)
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4142 ACS Reagent Chemicals, Part 4
