ANTIMONY PENTASULFIDE

Chemical properties

Antimony pentasulfide is an orange to dark red powder. It is doubtful whether stoichiometric Sb2S5 exists, because the preparations contain free sulfur and have variable composition. Antimony pentasulfide is insoluble in water but soluble in alkalies and alkali-metal carbonates.

Physical properties

Orange-yellow or reddish amorphous powder; density 4.12 g/cm³; decomposes at 75°C; insoluble in water and alcohol; soluble in hydrochloric acid, caustic alkalies and ammonium hydrosulfide.

The Uses of ANTIMONY PENTASULFIDE

As pigment; vulcanizing and coloring rubber; manufacture of matches and fireworks.

Preparation

The compound is made commercially by converting antimony trisulfide to tetrathioantimonate by boiling with sulfur in caustic soda solution:
4 Sb₂S₃ + 8 S +18 NaOH → 5 Na₃SbS₄ + 3 NaSbO₃ + 9 H₂O
The sparingly soluble sodium antimonate is filtered out of the solution. The yellow-orange antimony pentasulfide precipitates out on treatment with hydrochloric acid.
2 Na₃SbS₄ + 6 HCl → Sb₂S₅ + 6 NaCl + 3 H₂S
It may also be prepared by the reaction of antimony pentachloride in HCl with hydrogen sulfide and removing any free sulfur by extraction with carbon disulfide:
2 SbCl₅ + 5 H₂S → Sb₂S₅ + 10 HCl.

Definition

ChEBI: Antimony pentasulfide is a sulfide and a p-block molecular entity.

Hazard

Flammable, dangerous fire risk near oxi- dizing materials.

Safety Profile

Moderately toxic by intraperitoneal route. See also ANTIMONY COMPOUNDS and SULFIDES. Flammable when exposed to heat or by chemical reaction with powerful oxidtzers. Use water to fight fire. Moderately explosive when shocked or by spontaneous chemical reaction in contact with powerful oxidtzers. When heated to decomposition or on contact with acid or acid fumes it emits highly toxic fumes of oxides of sulfur and antimony. Incompatible with water or steam to produce toxic and flammable vapors and with oxidizers, e.g., Ag(ClO3)2, HClO3, ClO2, Mg(ClO3)2, TlO,Zn(ClO3)2.