Description of experiment
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Needed compounds:
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hydrochloric acid : HCl
sodium sulfide : Na2S . 3H2O
ferrous sulfate : FeSO4 . 7H2O
Class:
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elem=Fe,S
precipitation
Summary:
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Ferrous sulfide is a black precipitate, which easily dissolves in acid.
Description:
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Add a fresh solution of Na2S to a fresh solution of FeSO4.7H2O: A black
precipitate appears.
Add an excess amount of dilute hydrochloric acid (appr. 10% by weight):
The black precipitate almost immediately dissolves, the liquid becomes clear
and almost without color. A strong odour of H2S appears (rotten eggs).