What Is Sodium Sulfide?
Sodium sulfide (Na2S) is an inorganic compound, typically found as a hexahydrate. It forms strongly alkaline solutions due to hydrolysis and reacts with acids to produce hydrogen sulfide, necessitating careful handling.
Uses of Sodium Sulfide
Its applications span pharmaceuticals, food additives, lubricants for viscose human silk, leather dehairing, dyeing aids, PPS resin production, copper flotation, wastewater treatment, glass, and pulp production. It’s also used in small-scale experiments, semiconductor manufacturing, and in common products like desiccants and bath salts.
Properties of Sodium Sulfide
Deliquescent and highly water-soluble, sodium sulfide dissolves with exothermic reactions. It’s soluble in alcohol but insoluble in ether. Its anhydrous form melts at 950°C, while the hexahydrate and pentahydrate have lower melting points and decompose at high temperatures.
Structure of Sodium Sulfide
The anhydrous form has a cubic structure, with sodium ions occupying positions analogous to fluoride ions in calcium fluoride. The hydrates form colorless tetragonal crystals, with varying densities across different hydrate forms.
Other Information on Sodium Sulfide
1. Synthesis of Sodium Sulfide
Produced by reacting sodium hydroxide with hydrogen sulfide, heating hydrates in hydrogen, or direct reaction of sulfur with sodium. Industrially, it’s made by reducing sodium sulfate with coke.
2. Reaction of Sodium Sulfide
Reacts with air’s carbon dioxide and oxygen to form various sodium salts, and oxidizes to produce sodium sulfate. In aqueous solutions, it can dissolve sulfur to form polysulfides.
3. Characteristics of Sodium Tetrasulfide
Na2S4 is a yellow crystal soluble in water and ethanol, used in analytical reagents, desulfurizing agents, and more. It liberates sulfur when exposed to air and is corrosive and toxic.