Sodium sulfide
General
Name	Sodium Sulfide
Molecular formula	Na2S
Molar mass	78.046 g/mol
Appearance	colorless, hygroscopic solid
CAS number	*
Properties
Solubility in water	readily soluble
Solubility in alcohol	slightly soluble
pH	alkaline

Sodium sulfide is the name used to refer to the chemical compound Na₂S but more commonly its hydrate Na₂S^.9H₂O. Both are a colorless water-soluble salts that give strongly alkaline solutions. When exposed to moist air, Na₂S and its hydrates emit hydrogen sulfide, which smells much like rotten eggs.

Structure

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Na₂S adopts the "antifluorite" structure, which means that the Na⁺ centers occupy sites of the fluoride in the CaF₂ framework, and the larger S^2- occupy the sites for Ca²⁺. In solution, the salt, by definition, dissociates. The dianion S^2- does not, however, exist in appreciable amounts in water. Sulfide is too strong of a base to coexist with water. Thus, the dissolution process can be described as follows:

Na₂S + H₂O → Na⁺,SH^- + Na⁺,OH^-

Production

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Industrially Na₂S is produced by reduction of Na₂SO₄ with carbon, in the form of coal:Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.

Na₂SO₄ + 4 C → Na₂S + 4 CO

In the laboratory, the anhydrous salt can be prepared by reduction of sulfur with sodium in anhydrous ammonia:

2 Na + S → N₂S

Safety

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Na₂S and its hydrates are dangerous and should only be handled by experts. Like lye, it is strongly alkaline and will cause skin burns. Acids react rapidly to produce H₂S, which is a highly toxic gas. See hydrogen sulfide.

References

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External links

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• chemicalland21.com Sodium sulfide.

sulfides