Sodium Sulfide: Formulas, Uses, Risks

He Sodium sulfide (Na 2 S) is a yellow to red brick crystalline solid. In nature it is in different degrees of hydration, being the most common the sodium sulfide nonahidrato (Na2S · 9H2O).

They are water soluble salts that give strongly alkaline solutions. When exposed to moist air, they absorb moisture from the air, being able to spontaneously warm up and ignite nearby combustible materials. Also, in contact with the humid air, they emit hydrogen sulphide, which smells like rotten eggs.

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

Sodium monosulfide is commercially supplied as flakes 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 (Na 2 S) crystallizes with the antifluorite structure, where each S atom is surrounded by a cube of 8 Na atoms and each Na atom by a tetrahedron of 4 S atoms.

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

Inflammability

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

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

Reactivity

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

Toxicity

Many members of the inorganic sulphide group act as strong bases, and can cause severe burns upon contact with the skin.

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

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

Sodium sulphide is considered to be hazardous to the environment, especially to aquatic organisms.

Applications

At home, sodium sulfide is used in uncovering pipes, household cleaners (for the oven, the bathroom), hair straighteners, dishwasher soap and automotive airbags.

In industry, it is used in cleaners, 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 several products for the home in low concentration.

In developed countries, serious effects are rare. These occur mainly by the deliberate ingestion of the chemical in adults. However, and In developing countries, serious effects are more common.

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

Oral exposure

In the gastrointestinal tissue, initial inflammation occurs, followed by tissue necrosis (with possible perforation), then granulation and finally stenosis 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 stenosis (particularly esophageal).

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

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

They may develop: hypotension, tachycardia, tachypnea, esophageal (primarily esophageal) formation, esophageal carcinoma, and upper respiratory tract edema (which is common and often life threatening).

Severe intoxication is usually limited to deliberate intake in adults.

Inhalation exposure

Mild exposure may cause coughing and bronchospasm.

Severe inhalation may cause upper respiratory tract edema, Burns , Stridor and, in rare cases, acute lung injury.

Eye exposure

It can produce 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 may 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 through the use of globally consistent criteria.

The hazard classes (and their corresponding GHS chapter), classification and labeling standards, and 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).

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