Appearance and properties: Colorless, needle-shaped crystals that readily deliquesce. Commercial products are generally solutions that are orange or yellow and have a hydrogen sulfide odor.

Melting point: 350°C (anhydrous); it decomposes at its melting point, releasing hydrogen sulfide.

Flash point: 90°C.

Solubility: Readily soluble in water and alcohol. Its aqueous solution is strongly alkaline (solubility: 620 g/L at 20°C).

Stability: Decomposes rapidly in moist air into sodium hydroxide and sodium sulfide, releasing heat, and may ignite spontaneously. Reacts with acids to produce toxic and flammable hydrogen sulfide (H₂S) gas.

Product Applications

Sodium hydrosulfide is an important basic chemical raw material widely used in various industrial fields:

Dye industry: Used to synthesize organic intermediates and as an auxiliary in the production of sulfur dyes.

Tanning industry: Used for hair removal from raw hides and for tanning leather.

Mining industry: Used as a flotation reagent for ores such as copper ore.

Fertilizer industry: Used to remove elemental sulfur from activated-carbon desulfurization agents.

Wastewater treatment: Used to treat wastewater containing heavy metal ions by precipitating the metal ions.

Polymeric materials: Used as a raw material in the production of heat-resistant plastics (such as polyphenylene sulfide, PPS), flame-retardant resins, and rubber vulcanization accelerators.

Paper industry: Used in the kraft pulping process to provide sulfidity in the cooking liquor.

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