Chemical elements
    Physical properties
    Chemical properties
      Aluminium subfluoride
      Aluminium trifluoride
      Aluminium trichloride
      Aluminium tribromide
      Aluminium iodide
      Aluminium chlorate
      Aluminium perchlorate
      Aluminium bromate
      Aluminium periodate
      Aluminium suboxide
      Aluminium sesqui-oxide
      Aluminium peroxide
      Aluminium hydroxides
      Tricalcium aluminate
      Sodilim aluminate
      Aluminium sesqui-sulphide
      Aluminium selenide
      Aluminium telluride
      Aluminium sulphite
      Aluminium sulphate
      Sodium alum
      Potassium alum
      Ammonium alum
      Hydroxylamine alum
      Silver alum
      Aluminium dithionate
      Aluminium selenite
      Aluminium selenate
      Aluminium chromate
      Aluminium molybdate
      Aluminium silicomolybdate
      Aluminium tungstate
      Aluminium silicotungstate
      Aluminium phosphotungstate
      Aluminium nitride
      Aluminium phosphide
      Aluminium arsenide
      Aluminium nitrate
      Aluminium Phosphates
      Basic aluminium arsenite
      Aluminium carbide
      Aluminium carbonate
      Aluminium thiocyanate
      Aluminium oxalate
      Aluminium alkyls
      Aluminium Hydrocarbon
      Aluminium acetylacetonate
      Aluminium silicide
      Aluminium silicates
      Aluminosilicic acids aluminosilicates
      Aluminium Borides
      Aluminium Boride
      Aluminium Boride
      Aluminium borocarbides
      Aluminium borate
      Aluminium sodium perborate
    PDB 1a6e-1zca
    PDB 2b8w-3i62
    PDB 3kql-5ukd

Aluminium sesqui-sulphide, Al2S3

Aluminium sesqui-sulphide, Al2S3, was first obtained by Fremy by heating alumina to redness in a current of carbon disulphide vapour. It may be obtained by the action of hydrogen sulphide upon alumina at a red heat or by the action of sulphur on a heated mixture of alumina and carbon.

Aluminium sulphide is readily prepared by heating alumina with galena in a muffle furnace, or by the direct union of its elements. The powdered elements are mixed in a fireclay crucible, heated till the sulphur fuses, and cooled. The reaction is then brought about as in a thermit reaction by means of a firing powder ignited by a piece of magnesium ribbon. The sulphide is purified by sublimation in vacuo at 1100° to 1250°, or in nitrogen at 1500° to 1600°.

According to Biltz and Caspari, aluminium sulphide crystallises in white, asbestos-like needles (which are possibly hexagonal) and forms mixed crystals with alumina. It melts at 1100° ± 10° and its density at 13° is 2.02. Heated to 2100° in an inert atmosphere it loses sulphur and forms aluminium subsulphide, AlS; heated in air or oxygen it is converted into alumina and sulphur dioxide.

Aluminium sesqui-sulphide is rapidly and completely decomposed by water with the formation of aluminium hydroxide and hydrogen sulphide, a behaviour in accordance with the fact that it is the salt of a very weak, practically insoluble base and a very weak acid. The decomposition of the monosulphide by hydrochloric acid is represented by the equation: -

2AlS + 6HCl = 2AlCl3 + 2H2S + H2.

By heating a mixture of alumina and a carbonate to redness in a current of carbon disulphide vapour, the following double sulphides have been obtained: potassium-aluminium sulphide, 3K2S.Al2S3; sodium-aluminium sulphide, 3Na2S.Al2S3; and barium-, strontium-, and calcium-aluminium sulphides. Aluminium-silver sulphide, 4Ag2S.5Al2S3, melts at 1035°.

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