Sodium sulfide

Sodium sulfide
Sodium sulfide
CAS number 1313-82-2 YesY
1313-84-4 (pentahydrate)
1313-84-4 (nonahydrate)
PubChem 237873
EC number 215-211-5
UN number 1385 (anhydrous)
1849 (hydrate)
RTECS number WE1905000
Molecular formula Na2S
Molar mass 78.0452 g/mol (anhydrous)
240.18 g/mol (nonahydrate)
Appearance colorless, hygroscopic solid
Density 1.856 g/cm3 (anhydrous)
1.58 g/cm3 (pentahydrate)
1.43 g/cm3 (nonohydrate)
Melting point

1176 °C (anhydrous)
100 °C (pentahydrate)
50 °C (nonhydrate)

Solubility in water 186 g/L (20 °C)
390 g/L (50 °C)
Solubility insoluble in ether
slightly soluble in alcohol
Crystal structure Antifluorite (cubic), cF12
Space group Fm3m, No. 225
Tetrahedral (Na+); cubic (S2–)
EU Index 016-009-00-8
EU classification Corrosive (C)
Dangerous for the environment (N)
R-phrases R31, R34, R50
S-phrases (S1/2), S26, S45, S61
NFPA 704
NFPA 704.svg
>480 ºC
Related compounds
Other anions Sodium oxide
Sodium selenide
Sodium telluride
Other cations Lithium sulfide
Potassium sulfide
Related compounds Sodium hydrosulfide
 YesY sulfide (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Sodium sulfide is the name used to refer to the chemical compound Na2S, but more commonly it refers to the hydrate Na2S·9H2O. Both are 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 or flatus. Generally, commercially available sodium sulfide is not a unique chemical entity, but it is specified as Na2xH2O, where a weight percentage of Na2S is specified. Commonly available grades have around 60% Na2S by weight, which means that x is around 3. Such technical grades of sodium sulfide have a yellow appearance. These grades of sodium sulfide are marketed as 'sodium sulfide flakes'. Although the solid is yellow, solutions of it are colorless.



Fluorite structure

Na2S adopts the antifluorite structure,[1][2] which means that the Na+ centers occupy sites of the fluoride in the CaF2 framework, and the larger S2− occupy the sites for Ca2+. In solution, the salt, by definition, dissociates. The dianion S2− 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

Sodium sulfide can oxidize when heated to sodium carbonate and sulfur dioxide:

2 Na2S + 3 O2 + 2 CO2 → 2 Na2CO3 + 2 SO2


Industrially Na2S is produced by reduction of Na2SO4 with carbon, in the form of coal:[3]

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 THF with a catalytic amount of naphthalene:[4]

2 Na + S → Na2S


It is primarily used in pulp and paper industry in the kraft process . It is used in water treatment as an oxygen scavenger agent, in the photographic industry to protect developer solutions from oxidation, in textile industry as a bleaching, as a desulfurising and as a dechlorinating agent and in leather trade for the sulfitisation of tanning extracts. It is used in chemical manufacturing as a sulfonation and sulfomethylation agent. It is used in the production of rubber chemicals, sulfur dyes and other chemical compounds. It is used in other applications including ore flotation, oil recovery, food preservative, making dyes, and detergent.


Like sodium hydroxide, sodium sulfide is strongly alkaline and can cause skin burns. Acids react with it to rapidly produce hydrogen sulfide, which is a toxic and foul-smelling gas.


  1. ^ Zintl, E; Harder, A; Dauth, B. (1934). "Gitterstruktur der oxyde, sulfide, selenide und telluride des lithiums, natriums und kaliums". Z. Elektrochem. Angew. Phys. Chem. 40: 588–93. 
  2. ^ Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN 0-19-855370-6.
  3. ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
  4. ^ So, J.-H; Boudjouk, P; Hong, Harry H.; Weber, William P. (1992). "Hexamethyldisilathiane". Inorg. Synth.. Inorganic Syntheses 29: 30. doi:10.1002/9780470132609.ch11. ISBN 9780470132609. 

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Look at other dictionaries:

  • sodium sulfide — natrio sulfidas statusas T sritis chemija formulė Na₂S atitikmenys: angl. sodium disulfide; sodium sulfide rus. натрий сернистый; натрия сульфид ryšiai: sinonimas – dinatrio sulfidas …   Chemijos terminų aiškinamasis žodynas

  • sodium sulfide — noun : a sulfide of sodium; especially : a crystalline compound Na2S usually obtained by heating sodium sulfate with coal or hydrogen and used in dehairing hides, in the manufacture of sulfur dyes, as a solvent for these dyes, and as a reducing… …   Useful english dictionary

  • sodium sulfide — Chem. a yellow or brick red, crystalline, deliquescent, water soluble solid, Na2S, used chiefly in the manufacture of dyes, soaps, and rubber, as a depilatory for leather, and in the flotation of powdered lead and copper ores. * * * …   Universalium

  • Sodium hydrosulfide — IUPAC name Sodium hydrosulfide …   Wikipedia

  • Sodium hydroxide — Sodium hydroxide …   Wikipedia

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  • Sodium thiosulfate — Sodium thiosulfate …   Wikipedia

  • Sodium oxide — Sodium oxide …   Wikipedia

  • Sulfide — For other uses, see Sulphide (disambiguation). Sulfide Systematic name Sulfanediide …   Wikipedia

  • sulfide — /sul fuyd, fid/, n. Chem. a compound of sulfur with a more electropositive element or, less often, a group. [1830 40; SULF(UR) + IDE] * * * ▪ inorganic Introduction also spelled  sulphide    any of three classes of chemical compounds containing… …   Universalium

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