Antimony(III) sulfate

Antimony sulfate, Sb2(SO4)3, is a hygroscopic salt formed by reacting antimony or its compounds with hot sulfuric acid. It is used in doping of semiconductors and in the production of explosives and fireworks.

Structure
Antimony(III) sulfate consists of interconnected SbO6 octahedra, which the corners are bonded to the sulfate ion.

Production
Antimony(III) sulfate was first produced in 1827 by the reaction of antimony(III) oxide and 18 molar sulfuric acid at 200 °C:
 * Sb2O3 + 3 H2SO4 -> Sb2(SO4)3 + 3 H2O

The concentration of the sulfuric acid is important, as a lower concentration will produce basic antimony oxides, while a higher concentration will produce antimony(III) pyrosulfate. The reaction of elemental antimony and 18 M sulfuric acid will also produce antimony(III) sulfate:
 * 2 Sb + 6 H2SO4 -> Sb2(SO4)3 + 3 SO2 + 6 H2O

Chemical properties
Antimony sulfate is deliquescent, hydrolyzing in moist air and water, producing various basic antimony oxides and antimony(III) oxide. It is soluble in acids.

Uses
Owing to its solubility, antimony sulfate has uses in the doping of semiconductors. It is also used for coating anodes in electrolysis and in the production of explosives and fireworks.

Safety
Antimony(III) sulfate causes irritation to the skin and mucous membranes.

Natural occurrence
Natural analogue of the exact compound is yet unknown. However, basic hydrated Sb sulfates are known as the minerals klebelsbergite and coquandite.