Description of experiment
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Needed compounds:
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hydrochloric acid : HCl
sulphur : S8
sodium sulfide : Na2S . 3H2O
antimony sesquioxide : Sb2O3
Class:
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elem=Sb
coordination
Summary:
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Sulfide is capable of dissolving sulphur, forming intensely colored poly-
sulfide species. These poly-sulphide species react with antimony (III) in
strongly acidic environments, resulting in two different types of
precipitates.
Description:
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Add some sulphur to a solution of sodium sulfide: The sulphur partly dissolves.
The liquid becomes intense yellow and clear.
Boil for a while: More of the sulphur dissolves, the color of the liquid
becomes even more intense and it becomes brown/yellow.
Let liquid cool down again: The color shifts from brown/yellow to bright
yellow. The liquid remains clear.
Quickly pour the yellow liquid in an excess amount of a solution of Sb2O3
in HCl (appr. 10% by weight): Formation of a yellow and an orange precipitate.