Stannous Chloride
SnCl2·2H2O 225.65

Tin chloride (SnCl2) dihydrate [10025-69-1].
» Stannous Chloride dihydrate contains not less than 98.0 percent and not more than the equivalent of 102.0 percent of SnCl2·2H2O.
Packaging and storage— Preserve in well-closed containers. No storage requirements specified.
Identification—
A: To 0.40 g of Stannous Chloride, add 1 mL of dilute hydrochloric acid solution (236 mL of hydrochloric acid per L), and dilute with water to 20 mL. Keep a portion for the Limit of sulfate test. To 1 mL of this solution, add a mixture of 5 mL of water and 0.05 mL of mercuric chloride TS. A blackish-grey precipitate forms.
B: Dissolve 1.0 g of Stannous Chloride in 3.0 mL of water. Add 0.5 mL of dilute sodium hydroxide solution (85 g of sodium hydroxide per L) to the cloudy solution: a yellowish, flocculent precipitate is formed. Add 6.5 mL of water. To 1.0 mL of the previously shaken suspension, add 1.0 mL of stronger sodium hydroxide solution (420 g of sodium hydroxide per L): the precipitate dissolves, and the resulting solution is clear and colorless.
C: Dissolve 10 mg of Stannous Chloride in 2 mL of 20% nitric acid. The solution meets the requirements of the test for Chloride 191.
Appearance of solution— Dissolve 10.0 g of Stannous Chloride in dilute hydrochloric acid solution, and dilute with dilute hydrochloric acid to 20 mL. The solution is clear and colorless, or if not, not more intensely colored than a Reference solution prepared as follows:
Standard solution— Pipet 30.0 mL of ferric chloride CS, 30.0 mL of cobaltous chloride CS, and 24.0 mL of cupric sulfate CS into a 100-mL volumetric flask. Dilute with 1% (w/v) hydrochloric acid to volume, and mix.
Reference solution— Pipet 1.0 mL of Standard solution into a 100-mL volumetric flask. Dilute with 1% (w/v) hydrochloric acid to volume, and mix.
Substances not precipitated by thioacetamide— Dissolve 1.0 g of Stannous Chloride in dilute hydrochloric acid solution, and dilute with the same acid to 30 mL. Heat to boiling. Add 30 mL of thioacetamide TS, and boil for 15 minutes (Solution A). Filter 5 mL, and heat the filtrate to boiling. Add 5 mL of thioacetamide TS, and boil for 15 minutes. If a precipitate is formed, add the remainder of Solution A to the mixture to produce Solution A1. Add 10 mL of thioacetamide TS, and boil. Repeat the series of operations from “Filter 5 mL” until a precipitate is no longer formed on addition of thioacetamide TS to the filtrate obtained from the 5 mL of Solution A (Solution A1, Solution A2, ..., respectively). If no precipitate is formed, or if no more precipitate is formed, combine the solution obtained with the remainder of Solution A (Solution A1, Solution A2, ..., respectively), filter, and wash the precipitate with 10 mL of water. Heat the filtrate until the resulting vapor no longer turns a moistened piece of lead acetate test paper blackish-gray. Allow to cool, and dilute with water to 50 mL. Keep a portion for the Limit of iron test. Evaporate 25 mL of the solution to dryness, and ignite at 600. The residue weighs not more than 1 mg (0.2%).
Limit of sulfate—
Acetic acid solution— Dilute 30 mL of glacial acetic acid with water to 100 mL.
30% Alcohol— Dilute 30 mL of alcohol with water to 100 mL.
Potassium sulfate solution— Dissolve 1.8 g of potassium sulfate with 30% Alcohol to make 1000 mL.
Standard solution— Mix 3 mL of barium chloride solution (250 g per L) and 4.5 mL of Potassium sulfate solution. Shake, and let stand for 1 minute. To 2.5 mL of this solution, add 15 mL of Potassium sulfate solution and 0.5 mL of Acetic acid solution. Allow to stand for 5 minutes.
Test solution— Use 15 mL of the solution prepared in Identification A.
Procedure— Mix 3 mL of barium chloride solution (250 g per L) and 4.5 mL of Potassium sulfate solution. Shake, and let stand for 1 minute. To 2.5 mL of this solution, add the Test solution and 0.5 mL of Acetic acid solution. Allow to stand for 5 minutes. Any opalescence in the Test solution is not more intense than that in the Standard solution (500 ppm).
Limit of iron—
Standard Iron Solution— Prepare as directed for Special Reagents under Iron 241.
Standard solution— Immediately before use, dilute 1 mL of Standard Iron Solution to 10 mL with water. This solution contains the equivalent of 1 µg of iron per mL.
Test solution— Dilute 5 mL of the solution prepared in Substances not precipitated by thioacetamide with water to 10 mL.
Procedure— To 10 mL each of the Standard solution and the Test solution, add 2 mL of dilute citric acid (200 g per L) and 0.1 mL of thioglycolic acid, and mix. Make alkaline with a dilute ammonia solution (620 mL of ammonium hydroxide per L). Dilute with water to 20 mL. Allow the treated Standard solution and the treated Test solution to stand for 5 minutes. Any pink color in the Test solution is not more intense than that in the Standard solution (100 ppm).
Limit of lead—
Dilute thioacetamide solution— To 0.2 mL of thioacetamide TS, add 1 mL of a mixture of 5 mL of water, 15 mL of 1 N sodium hydroxide, and 20 mL of 85% glycerin. Heat in a water bath for 20 seconds. [note—Prepare immediately before use.]
Standard Lead Solution— Prepare as directed for Special Reagents under Heavy Metals 231.
Standard solution— On the day of use, mix 1.0 mL of Standard Lead Solution, 6 mL of water, 3 mL of stronger sodium hydroxide solution (420 g of sodium hydroxide per L), and 0.5 mL of Dilute thioacetamide solution.
Procedure— Dissolve 1.0 g of Stannous Chloride in 2 mL of a mixture of 1 volume of nitric acid and 3 volumes of hydrochloric acid. Heat the solution on a water bath until nitrous vapor is no longer evolved. Dissolve the residue in water, and dilute with water to 25 mL. To 5 mL of this solution, add 3 mL of stronger sodium hydroxide solution and 2 mL of water. Heat until a clear solution is obtained, cool, and add 0.5 mL of Dilute thioacetamide solution. Allow to stand for 2 minutes. Any color in this solution is not more intense than that in the Standard solution (50 ppm).
Assay— Dissolve about 0.1 g of Stannous Chloride, accurately weighed, in 50 mL of water, freed from oxygen by purging with carbon dioxide or nitrogen for 15 minutes prior to the addition. Add 1.5 mL of 0.8 N hydrochloric acid, 5 g of potassium sodium tartrate, 10 g of sodium bicarbonate, and 1 mL of starch TS. Titrate immediately with 0.05 N iodine VS. Perform a blank determination (see Residual Titrations under Titrimetry 541): 1 mL of 0.05 N iodine VS is equivalent to 11.28 mg of SnCl2·2H2O.
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