Page 24 - Curriculum Visions Dynamic Book

Hydrogen sulphide
Hydrogen sulphide gas burns with a blue flame. It is a reducing agent, taking oxygen from some of the compounds with which
it reacts. It is poorly soluble in water, but when dissolved will produce a solution of hydrogen sulphide with a smell of bad eggs.
When hydrogen sulphide reacts with other compounds, the new sulphide compounds are characteristically black in colour (the exceptions are pyrite, which is yellow,
and cadmium sulphide, which is orange). When passed over a solution of a lead salt, hydrogen sulphide will produce a precipitate of black lead sulphide. This is a laboratory test for hydrogen sulphide.
Preparing hydrogen sulphide in the laboratory
Hydrogen sulphide is normally prepared by adding dilute hydrochloric acid to iron sulphide.
 Lead nitrate and hydrogen sulphide produce a black precipitate of lead sulphide (the mineral form of this is galena).
 Cobalt sulphide.
Chlorine
◆
➪ FeCl2(aq) + H2S(g) ◆
EQUATION: Preparing hydrogen sulphide
Dilute hydrochloric acid + iron sulphide ➪ ferric chloride + hydrogen sulphide
2HCl(aq) + FeS(s)
Sulphur
Hydrogen
+➡+ Iron
Hydrogen sulphide molecule
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