General Description
SODIUM SULFIDE, ANHYDROUS(1313-82-2) is a yellow to brick red crystalline mass or fused solid with an odor of rotten eggs. If exposed to moist air SODIUM SULFIDE, ANHYDROUS(1313-82-2) is liable to spontaneous heating and may cause ignition of nearby combustible material. SODIUM SULFIDE, ANHYDROUS(1313-82-2) absorbs moisture from the air.
Reactivity Profile
SODIUM SULFIDE is a white to yellow crystalline material, flammable. Can explode on rapid heating or when shocked. Violent reaction with carbon, charcoal, diazonium salts, N,N-dichloromethylamine, strong oxidizers, water. On contact with acids SODIUM SULFIDE, ANHYDROUS liberates highly toxic and flammable hydrogen sulfide gas. When heated to decomposition SODIUM SULFIDE, ANHYDROUS emits toxic fumes of sodium oxide, and oxides of sulfur [Bretherick, 5th ed., 1995, p. 1729].
Air & Water Reactions
Aqueous solutions of sodium sulfide when exposed to air slowly convert to sodium hydroxide and sodium thiosulfate. The crystalline form upon exposure to air forms hydrogen sulfide and sodium carbonate [Merck 11th ed. 1989].
Hazard
Flammable, dangerous fire and explosion
risk. Strong irritant to skin and tissue, liberates toxic
hydrogen sulfide on contact with acids.
Health Hazard
Caustic action on skin and eyes. If ingested may liberate hydrogen sulfide in stomach.
Fire Hazard
Special Hazards of Combustion Products: Irritating sulfur dioxide is produced in fire.
Physical properties
White cubic crystal; hygroscopic; density 1.856 g/cm3; melts at 1,172°C; soluble in water 18.6 g/100mL at 20°C and 39 g/100mL at 50°C; aqueous solutions strongly alkaline; slightly soluble in alcohol; insoluble in ether.
The pentahydrate consists of flat, shiny prismatic crystals; density 1.58 g/cm3; loses three water molecules at 100°C; melts at 120°C losing all water molecules; soluble in water and alcohol; aqueous solutions strongly alkaline; insoluble in ether.
The nonahydrate is a yellowish-white crystalline solid; tetragonal crystals; odor of hydrogen sulfide; the color changes on exposure to light and air, first turning to yellow and then becoming brownish-black, deliquescent; density 1.43 g/cm3; decomposes at about 50°C; very soluble in water; aqueous solution strongly alkaline; slightly soluble in alcohol; insoluble in ether.
Definition
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.
Definition
ChEBI: A sulfide salt with formula Na2S. The pentahydrate and (particularly) the nonahydrate are also known. In gel form, sodium sulfide is used to soften toenails to assist in trimming (and so relive pain) of ingrowing toenails.
Preparation
Sodium sulfide is prepared by heating sodium bisulfate with sodium chloride and coal above 950°C. The product mixture is extracted with water and the hydrated sulfide is obtained from the solution by crystallization: NaHSO4 + NaCl + 2C → Na2S + 2CO2↑ + HCl↑
Sodium sulfide also is produced from its elements in liquid ammonia: Na + 2S → Na2S.
Flammability and Explosibility
Nonflammable(100%)
Industrial uses
In non-metallic flotation, sodium sulfide is also used as a depressant and for collector
desorption, in particular, fatty acids from monazite, pyrochlore, zircon and microcline.
As a depressant for quartz, sodium sulfide is an excellent depressant for iron-activated
quartz as well as non-activated quartz.
Industrial uses
Sodium sulfide (Na2S·9H2O) is a hygroscopic substance with a specific gravity of 1.864
and a melting temperature of 1180 °C. The reagent is soluble in water. The aqueous solution
of sodium sulfide has a highly alkaline reaction resulting from its hydrolysis:
Na2S + H2O ? NaOH + NaHS
Purification Methods
Some purification of the hydrated salt can be achieved by selecting large crystals and removing the surface layer (contaminated with oxidation products) by washing with distilled water. Other metal ions can be removed from Na2S solutions by passage through a column of Dowex ion-exchange A-1 resin, Na+-form. The hydrated salt can be rendered anhydrous by heating it in a stream of H2 or N2 until water is no longer evolved. (The resulting cake should not be heated to fusion because it is readily oxidised.) Recrystallise it from distilled water [Anderson & Azowlay J Chem Soc, Dalton Trans 469 1986]. Note that sodium sulfide hydrolyses in H2O to form NaHS + H2O, and is therefore alkaline. A 0.1N solution in H2O is 86% hydrolysed at room temperature. Its solubility in H2O is 8% at 0o, 12% at 20o and 30% at 50o. The anhydrous salt is obtained by allowing it to stand in a vacuum over conc H2SO4 or P2O5 at 45o to start with, then at 30-35o when the salt contains 4% of water. The last traces of water are removed by heating to 700o in a glass or porcelain tube in a stream of H2 to give pure H2S. [Fehér in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I pp 358-360 1963.]