Ferric Chloride
FeCl3･6H2O
Mol. Wt. 270.30
ferric chloride hexahydrate
Content
〔hexahydrate 10025-77-1〕
Ferric Chloride contains 98.5−102.0% of ferric chloride (FeCl3･6H2O).
Description
Ferric Chloride occurs as deliquescent yellow-brown crystals or
lumps.
Identification
Ferric Chloride responds to all tests for Ferric Salt and for
Chloride as described in the Qualitative Tests.
Purity
(1)
Clarity of solution
Very slightly turbid.
Weigh 1.0 g of Ferric Chloride, add 10 ml of diluted hydrochloric acid (1 → 100),
and dissolve by heating.
(2)
Free acid
Weigh 2.0 g of Ferric Chloride, dissolve in 5 ml of water, and bring
a glass rod wetted with aqueous ammonia close to it. No white fumes are evolved.
(3)
Nitrate
Weigh 5 g of Ferric Chloride, dissolve in 25 ml of water, boil, and
add 25 ml of aqueous ammonia. After cooling, add water to make 100 ml, and filter.
Use this solution as the sample solution. Measure 5 ml of the sample solution, and add
5 ml of water, 0.1 ml of indigo carmine TS, and 10 ml of sulfuric acid. A blue color
persists for not less than 5 minutes.
(4)
Sulfate
Not more than 0.019% as SO4.
Test Solution Measure 20 ml of the sample solution prepared under (3) above,
add 3 ml of anhydrous sodium carbonate solution (1 → 8), evaporate to dryness in a
water bath, and heat over a small flame until the white fumes are no longer evolved.
After cooling, add 10 ml of water and 3 ml of diluted hydrochloric acid (1 → 4),
evaporate to dryness in a water bath, dissolve in 0.3 ml of diluted hydrochloric acid (1
→ 4) and water to make 50 ml.
Control Solution
To 0.40 ml of 0.005 mol/l sulfuric acid, add 1 ml of diluted
hydrochloric acid (1 → 4) and water to make 50 ml.
(5)
Heavy metals
Test Solution
Not more than 20 µg/g as Pb.
Weigh 1.0 g of Ferric Chloride, transfer into a porcelain dish,
dissolve with 3 ml of aqua regia, and evaporate to dryness in a water bath. Dissolve the
residue with 5 ml of diluted hydrochloric acid (1 → 2), and transfer the solution into a
separating funnel. Wash the porcelain dish twice with 5 ml of diluted hydrochloric acid
(1 → 2) each time, and transfer the washings into the separating funnel. Wash the
water layer twice with 40 ml of ether each time and again once with 20 ml of ether,
discard the washings, dissolve 0.05 g of hydroxylamine hydrochloride in the water
layer, heat in a water bath for 10 minutes, add 1 drop of phenolphthalein TS, and add
aqueous ammonia until a pink color develops. After cooling, add dropwise diluted
hydrochloric acid (1 → 2) until the solution becomes almost completely colorless, and
add 4 ml of diluted acetic acid (1 → 20) and water to make 50 ml.
Control Solution
Measure 2.0 ml of Lead Standard Solution, transfer into a
porcelain dish, add 3 ml of aqua regia, and proceed in the same manner as the sample.
(6)
Zinc
Not more than 30 µg/g as Zn.
Test Solution Measure 20 ml of the sample solution prepared under test (3) above,
transfer into a Nessler tube, neutralize with hydrochloric acid, add water to make 30
ml, and add 3 ml of diluted hydrochloric acid (1 → 4) and 0.2 ml of freshly prepared
potassium ferrocyanide solution (1 → 10).
Control Solution
Measure 3.0 ml of Zinc Standard Solution, transfer into a
Nessler tube, add water to make 30 ml, and proceed in the same manner as the sample
solution.
Procedure Allow the test solution and the control solution to stand for 15 minutes.
The test solution is not more turbid than the control solution.
(7)
Arsenic
Not more than 4.0 µg/g as As2O3.
Test Solution Weigh 0.50 g of Ferric Chloride, dissolve in 20 ml of water, and dissolve
0.2 g of L-ascorbic acid in the solution.
Standard
Color
Measure 1.0 ml of Arsenic Standard Solution, add 20 ml of
water, then dissolve 0.2 g of L-ascorbic acid in this solution.
Apparatus Appratus B.
Procedure Perform the test without neutralizing with aqueous ammonia.
(8)
Free chlorine
Weigh 2.0 g of Ferric Chloride, dissolve in 5 ml of water, heat,
and bring a filter paper wetted with zinc iodide−starch TS close to it. No blue color
develops.
Assay
Weigh accurately about 0.6 g of Ferric Chloride, transfer into a flask with
a ground-glass stopper, dissolve in about 50 ml of water, add 3 ml of hydrochloric acid
and 3 g of potassium iodide, immediately stopper tightly, allow to stand for 15 minutes
in a dark place, and titrate with 0.1 mol/l sodium thiosulfate (indicator: starch TS).
Perform a blank test in the same manner, and make any necessary correction.
1 ml of 0.1 mol/l sodium thiosulfate = 27.030 mg of FeCl3･6H2O