SODIUM SULFIDE: FORMULAS, USES, RISKS - CHEMISTRY - 2025

The sodium sulfide (Na2S) is a crystalline solid brick yellow to red. In nature it is found in different degrees of hydration, the most common being sodium sulphide nonahydrate (Na2S · 9H2O).

They are soluble salts in water that give strongly alkaline solutions. When exposed to humid air, they absorb moisture from the air, being able to heat up spontaneously and cause ignition of nearby combustible materials. Likewise, in contact with humid air, they emit hydrogen sulfide, which smells like rotten eggs.

They are strong reducing agents. These substances can be dangerous for the environment, especially for aquatic organisms.

Sodium monosulfide is supplied commercially in flake form containing 60-62% Na ₂ S..

• Formulas

• CAS: 1313-82-2 Sodium sulfide (anhydrous)
• CAS: 1313-84-4 Sodium sulfide (nonahydrate)

2D structure

Sodium sulfide

Sodium monosulfide nonahydrate

3D structure

Sodium sulfide

Sodium sulfide nonahydrate

Characteristics of sodium sulfide

Physical and chemical properties

Sodium monosulfide (Na2S) crystallizes with the antifluorite structure, in which each S atom is surrounded by a cube of 8 Na atoms and each Na atom by a tetrahedron with 4 S atoms.

Fluorite unit cell 3D ionic / It belongs to the group of inorganic sulfides.

Inflammability

The only highly flammable member in the group of inorganic sulfides is hydrogen sulfide. However, some other inorganic sulfides, such as sodium sulfide, can spontaneously heat up and even ignite if exposed to moisture.

When exposed to fire, sodium sulfide releases sulfur dioxide gases or vapors, which are irritating or toxic.

Reactivity

• Inorganic sulfides are generally basic (some are strongly basic, and therefore incompatible with acids).
• Many of these compounds are reducing agents (they react vigorously with oxidizing agents).
• Simple sulfide salts (such as sodium, potassium, and ammonium sulfide) react vigorously with acids to release highly toxic and flammable hydrogen sulfide gas.
• Sodium Sulfide is flammable. May explode when heated rapidly or struck.
• When heated to decomposition, it emits toxic vapors of sodium oxide and sulfur oxides.
• Reacts violently with carbon, charcoal, diazonium salts, N, N-dichloromethylamine, strong oxidants, and water.

Many members of the inorganic sulfide group behave like strong bases, and can cause severe burns on contact with skin.

This property depends on its solubility. The more insoluble inorganic sulfides (eg, mercury (II) sulfide and cadmium sulfide) are not caustic.

Sodium sulfide has a medium octanol / water (Pow) partition coefficient (-3.5). This value is used as a measure of the solubility (and bioconcentration) of a substance in animal fatty tissues (especially aquatic animals).

Sodium sulfide is considered dangerous for the environment, especially for aquatic organisms.

Applications

In the home, sodium sulfide is used in drain cleaners, household cleaners (for the oven, bathroom), hair straighteners, dishwasher soap, and automobile air bags.

In industry, it is used in cleaners, in cement, and as a precursor in the production of other chemicals.

Clinical effects

Exposure to sodium sulfide is common in developed and underdeveloped countries, both in industry and at home. These corrosive substances are present in various household products in low concentration.

In developed countries, serious effects are rare. These occur primarily from deliberate ingestion of the chemical in adults. However, in developing countries, severe effects are more common.

Alkaline corrosives cause liquefaction necrosis. They saponify the fats in the cell membrane, destroying the cell and allowing deep penetration into the mucous tissue.

Oral exposure

Initial inflammation occurs in the gastrointestinal tissue, followed by tissue necrosis (with possible perforation), then granulation, and finally stricture formation.

Patients with mild ingestion develop grade I irritation or burns (superficial hyperemia and edema) of the oropharynx, esophagus, or stomach.

Patients with moderate intoxication may develop grade II burns (superficial blisters, erosions, and ulcerations) with possible subsequent formation of strictures (particularly esophageal).

Some patients (especially young children) may develop upper respiratory edema.

Patients with severe intoxication by ingestion may develop deep burns and necrosis of the gastrointestinal mucosa, with complications such as: perforation (esophageal, gastric, rarely duodenal), fistula formation (tracheoesophageal, aortoesophageal) and gastrointestinal bleeding.

Hypotension, tachycardia, tachypnea, stricture formation (mainly esophageal), esophageal carcinoma, and upper respiratory edema (which is common and often life-threatening) can develop.

Severe poisoning is generally limited to deliberate ingestions in adults.

Inhalation exposure

Mild exposure can cause coughing and bronchospasm.

Severe inhalation can cause upper respiratory edema, burns, stridor and, rarely, acute lung injury.

Ocular exposure

It can cause severe conjunctival irritation and chemosis, corneal epithelial defects, limbic ischemia, permanent visual loss and in severe cases of perforation.

Dermal exposure

Mild exposure causes irritation and partial thickness burns. Metabolic acidosis can develop in patients with severe burns or shock.

Prolonged exposure or high concentration products can cause full thickness burns.

Safety and Risks

Hazard statements of the Globally Harmonized System of Classification and Labeling of Chemicals (GHS)

The Globally Harmonized System of Classification and Labeling of Chemicals (GHS) is an internationally agreed system, created by the United Nations and designed to replace the various classification and labeling standards used in different countries by using consistent criteria globally.

The hazard classes (and their corresponding GHS chapter), the classification and labeling standards, and the recommendations for sodium sulfide are as follows (European Chemicals Agency, 2017; United Nations, 2015; PubChem, 2017):

(United Nations, 2015, p.366).

(United Nations, 2015, p.370).

(United Nations, 2015, p.371).

(United Nations, 2015, p.374).

(United Nations, 2015, p.381).

(United Nations, 2015, p.384) (United Nations, 2015, p.381).

(United Nations, 2015, p.399).

References

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12. National Center for Biotechnology Information. PubChem Compound Database. (2016). Sodium Sulfide enneahydrate - PubChem Structure Retrieved from: pubchem.ncbi.nlm.nih.gov.
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