Sodium sulfide

Crystal structure
	Na + : __ / S 2− : __
Crystal system	Antifluorite (cubic)
Space group	Fm 3 m (No. 225)
General
Surname	Sodium sulfide
other names	Sulfur sodium; Disodium sulfide; Sulfigran; Sodium monosulfide;
Ratio formula	Na 2 S
Brief description	colorless, hygroscopic solid
External identifiers / databases
EC number	215-211-5
ECHA InfoCard	100,013,829
PubChem	14804
Wikidata	Q407510
properties
Molar mass	78.05 g mol −1 (anhydrous) ; 240.18 g mol −1 (nonahydrate)
Physical state	firmly
density	1.86 g cm −3 (14 ° C); 1.43 g cm −3 (as nonahydrate);
Melting point	1180 ° C
solubility	good in water (188 g l −1 at 20 ° C)
safety instructions
H and P phrases	H: 290-301-311-314-400
	EUH: 031-071
	P: 280-301 + 330 + 331-303 + 361 + 353-305 + 351 + 338-310
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Sodium sulfide , Na ₂ S, is a salt of hydrogen sulfide H ₂ S, a very weak acid.

Extraction and presentation

Substances containing sulfur (e.g. sodium sulfate) are reduced to sodium sulfide by glowing with charcoal powder and soda . It is also formed when hydrogen sulfide is introduced into sodium hydroxide solution . In the desiccator using sulfuric acid or phosphoric acid , the water content can be reduced to 4 percent. The remaining water can only be removed by heating to 700 ° C in hydrogen .

In the laboratory, the anhydrous salt can be produced by reducing sulfur with sodium in anhydrous ammonia .

{\ displaystyle \ mathrm {2 \ Na + S \ rightarrow Na_ {2} S}}

properties

Sodium sulfide crystals, technical grade.

In its pure state, sodium sulfide is a colorless, crystalline solid that smells like rotten eggs and is present as the nonahydrate Na ₂ S · 9 H ₂ O. The water-free version is odorless. Contact with acid (including carbon dioxide CO ₂ in the air we breathe) releases the toxic and flammable hydrogen sulfide (smell!). Finely distributed sodium sulfide , free of water of crystallization , can self-ignite in the air; it reacts violently with oxidizing agents such as potassium permanganate or potassium dichromate . It is readily soluble in water, the solution has a strong alkaline reaction and is very corrosive. The hydrates of sodium sulfide are not flammable, but lose the bound water when heated. When stored for a long time, the substance turns yellowish due to slow oxidation with the formation of polysulphides . Sodium sulfide crystallizes in an antifluorite structure ( cubic symmetry , space group Fm 3 m (space group no. 225) ), with the lattice parameter a = 6.526 Å . At 7 GPa it goes into a high pressure form with an anti-PbCl ₂ structure (space group Pnma (No. 62) ), at 16 GPa into a form with a Ni ₂ In structure (space group P 6 ₃ / mmc (No. 194) ) over. Template: room group / 225 Template: room group / 62Template: room group / 194

use

Sodium sulphide is used, among other things, in the tannery as a depilatory agent , in mining for ore flotation , in organic chemistry as a reducing agent , in wastewater treatment for heavy metal precipitation and for the production of sulfur dyes. It is also used to color glass, remove NO _x ( nitrogen oxides ) from exhaust gases and break down wood . In black and white photography and lithography, it is used in the darkroom for sulfur toning ( sepia toning ).

Individual evidence

↑ ^a ^b Eduard Zintl , A. Harder, B. Dauth: Lattice structure of the oxides, sulfides, selenides and tellurides of lithium, sodium and potassium. In: Journal of Electrochemistry and Applied Physical Chemistry , 40, 1934, pp. 588-593.
↑ ^a ^b ^c ^d ^e ^f Entry on sodium sulphide in the GESTIS substance database of the IFA , accessed on January 10, 2017(JavaScript required) .
↑ ^a ^b Entry on sodium sulfide. In: Römpp Online . Georg Thieme Verlag, accessed on November 10, 2014.
↑ Entry on Disodium sulphide in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
↑ G. Brauer (Ed.), Handbook of Preparative Inorganic Chemistry 2nd ed., Vol. 1, Academic Press 1963, pp. 358-60.
↑ J.-H. So, P. Boudjouk: Hexamethyldisilathiane . In: Inorganic Syntheses . 1992, 29, p. 30, doi : 10.1002 / 9780470132609.ch11 .
↑ A. Vegas, A. Grzechnik, M. Jansen, M. Hanfland, I. Loa, K. Syassen: Reversible phase transitions in Na ₂ under pressure S: a comparison with the cation array in Na ₂ SO ₄ . In: Acta Crystallographica , B57, 2001, pp. 151-156, doi: 10.1107 / S0108768100016621 .

[Zintl-1] Eduard Zintl , A. Harder, B. Dauth: Lattice structure of the oxides, sulfides, selenides and tellurides of lithium, sodium and potassium. In: Journal of Electrochemistry and Applied Physical Chemistry , 40, 1934, pp. 588-593.

[GESTIS-2] ↑ ^a ^b ^c ^d ^e ^f Entry on sodium sulphide in the GESTIS substance database of the IFA , accessed on January 10, 2017(JavaScript required) .

[Römpp-3] Entry on sodium sulfide. In: Römpp Online . Georg Thieme Verlag, accessed on November 10, 2014.

[CLP_100.013.829-4] Entry on Disodium sulphide in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .

[5] G. Brauer (Ed.), Handbook of Preparative Inorganic Chemistry 2nd ed., Vol. 1, Academic Press 1963, pp. 358-60.

[6] J.-H. So, P. Boudjouk: Hexamethyldisilathiane . In: Inorganic Syntheses . 1992, 29, p. 30, doi : 10.1002 / 9780470132609.ch11 .

[7] A. Vegas, A. Grzechnik, M. Jansen, M. Hanfland, I. Loa, K. Syassen: Reversible phase transitions in Na ₂ under pressure S: a comparison with the cation array in Na ₂ SO ₄ . In: Acta Crystallographica , B57, 2001, pp. 151-156, doi: 10.1107 / S0108768100016621 .