Sodium Sulfide USP Grade Specifications
Na2S.9H2O -- 240.18
Sodium sulfide nonahydrate.
Disodium sulfide nonahydrate [CAS 1313-84-4].

Sodium Sulfide contains not less than 98.0 percent and not more than 103.0 percent of Na2S.9H2O.

Identification: [NOTE: Conduct this test in a fume hood.] Transfer about 100 mg of Sodium Sulfide, to a suitable container, add 10 mL of 3 N hydrochloric acid, and cover the top of the container with filter paper saturated with a 0.2 M lead acetate solution: a brownish or silvery-black color forms on the paper.
Limit of iron: Dissolve about 5.0 g in 100 mL of water: the solution is clear and colorless.
Limit of sulfite and thiosulfate: Dissolve 3.0 g in 200.0 mL of filtered and degassed water. Add 100.0 mL of 0.2 N zinc sulfate, mix, and allow to stand for 30 minutes. Filter, add 1 mL of starch, and titrate 100.0 mL of the filtrate with 0.01 N iodine: not more than 3.0 mL is required.

Sodium Sulfide Nonahydrate Analytical Reagent Grade Specifications
Na2S-9H2O --- Formula Weight 240.18
CAS Number 1313-84-4
NOTE: To enhance stability, storage below 10C is recommended.

REQUIREMENTS
Appearance: Crystals, colorless or with only a slight yellow color
Assay: 98.0% Na2S-9H2O

MAXIMUM ALLOWABLE
Ammonium (NH4): 0.005%
Sulfite and thiosulfate (as SO4): 0.1%
Iron: Passes test.