Sodium sulfide is the name used to refer to the
chemical compoundA chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
Na
2S but more commonly its hydrate Na
2S
.9H
2O. Both are colorless water-soluble salts that give strongly alkaline solutions. When exposed to moist air, Na
2S and its hydrates emit
hydrogen sulfideHydrogen sulfide is the chemical compound with the formula H
2S. This colorless, toxic and flammable gas is partially responsible for the foul odor of rotten eggs and flatulence....
, which smells much like rotten eggs.
Na
2S adopts the antifluorite structure, which means that the Na
+ centers occupy sites of the fluoride in the CaF
2 framework, and the larger S
2− occupy the sites for Ca
2+.
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Sodium sulfide is the name used to refer to the
chemical compoundA chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
Na
2S but more commonly its hydrate Na
2S
.9H
2O. Both are colorless water-soluble salts that give strongly alkaline solutions. When exposed to moist air, Na
2S and its hydrates emit
hydrogen sulfideHydrogen sulfide is the chemical compound with the formula H
2S. This colorless, toxic and flammable gas is partially responsible for the foul odor of rotten eggs and flatulence....
, which smells much like rotten eggs.
Structure
Na
2S adopts the antifluorite structure, which means that the Na
+ centers occupy sites of the fluoride in the CaF
2 framework, and the larger S
2− occupy the sites for Ca
2+. In solution, the salt, by definition, dissociates. The dianion S
2− does not, however, exist in appreciable amounts in water. Sulfide is too strong a base to coexist with water. Thus, the dissolution process can be described as follows:
- Na2S(s) + H2O(l) → 2Na+(aq) + HS− + OH−
Production
Industrially Na
2S is produced by reduction of
Na2SO4Sodium sulfate is the sodium salt of sulfuric acid. Anhydrous, it is a white crystalline solid of formula Na
2SO
4 known as the mineral thenardite; the decahydrate Na
2SO
4·10H
2O has been known as Glauber's salt or, historically, sal mirabilis...
with carbon, in the form of coal:
- Na2SO4 + 4 C → Na2S + 4 CO
In the laboratory, the anhydrous salt can be prepared by reduction of sulfur with sodium in anhydrous ammonia. Alternatively, sulfur can be reduced by sodium in dry
THFTetrahydrofuran is a colorless, water-miscible organic liquid with low viscosity at standard temperature and pressure. This heterocyclic compound has the chemical formula 4O. As one of the most polar ethers with a wide liquid range, it is a useful solvent. Its main use is however as a...
with a catalytic amount of
naphthaleneNaphthalene, also known as naphthalin, or antimite and not to be confused with naphtha, is a crystalline, aromatic, white, solid hydrocarbon with formula C
10H
8 and the structure of two fused benzene rings. It is best known as the traditional, primary ingredient of mothballs...
:
- 2 Na + S → Na2S
Safety
Like
sodium hydroxideSodium hydroxide , also known as lye and caustic soda, is a caustic metallic base. It is used in many industries, mostly as a strong chemical base in the manufacture of pulp and paper, textiles, drinking water, soaps and detergents and as a drain cleaner. Worldwide production in 1998 was around...
, sodium sulfide is strongly alkaline and can cause skin burns. Acids react with it to rapidly produce
hydrogen sulfideHydrogen sulfide is the chemical compound with the formula H
2S. This colorless, toxic and flammable gas is partially responsible for the foul odor of rotten eggs and flatulence....
, which is a toxic and foul-smelling gas.
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