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sodium sulfide

 
Dictionary: sodium sulfide
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n.
A hygroscopic yellow compound, Na2S, used as a metal ore reagent and in photography, engraving, and printing.


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Chemistry Dictionary: sodium sulphide
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A yellow-red solid, Na2S, formed by the reduction of sodium sulphate with carbon (coke) at elevated temperatures. It is a corrosive and readily oxidized material of variable composition and usually contains polysulphides of the type Na2S2, Na2S3, and Na2S4, which cause the variety of colours. It is known in an anhydrous form (r.d. 1.85; m.p. 1180°C) and as a nonahydrate, Na2S.9H2O (r.d. 1.43; decomposes at 920°C). Other hydrates of sodium sulphide have been reported. The compound is deliquescent, soluble in water with extensive hydrolysis, and slightly soluble in alcohol. It is used in wood pulping, dyestuffs manufacture, and metallurgy on account of its reducing properties. It has also been used for the production of sodium thiosulphate (for the photographic industry) and as a depilatory agent in leather preparation. It is a strong skin irritant.


Wikipedia: Sodium sulfide
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Sodium sulfide
Fluorite-unit-cell-3D-ionic.png
Other names Disodium sulfide
Identifiers
CAS number 1313-82-2 Yes check.svgY,
1313-84-4 (pentahydrate)
1313-84-4 (nonahydrate)
PubChem 237873
EC number 215-211-5
UN number 1385 (anhydrous)
1849 (hydrate)
RTECS number WE1905000
Properties
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 18.6 g/100 mL (20 °C)
39 g/100 mL (50 °C)
Solubility insoluble in ether
slightly soluble in alcohol
Structure
Crystal structure Antifluorite (cubic), cF12
Space group Fm3m, No. 225
Coordination
geometry		 Tetrahedral (Na+); cubic (S2–)
Hazards
MSDS ICSC 1047
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
1
3
1
 
Autoignition
temperature		 >480 ºC
Related compounds
Other anions Sodium oxide
Sodium selenide
Sodium telluride
Other cations Lithium sulfide
Potassium sulfide
Related compounds Sodium hydrosulfide
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 its 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.

Contents

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−

Production

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

Safety

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.

References

  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 (1992). "Hexamethyldisilathiane". Inorg. Synth. 29: 30. doi:10.1002/9780470132609.ch11. 

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Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.  Read more
Chemistry Dictionary. A Dictionary of Chemistry. Sixth Edition. Copyright © Market House Books Ltd, 2008. All rights reserved.  Read more
Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Sodium sulfide".  Read more