Page 37 - Curriculum Visions Dynamic Book

The gelatinous precipitate of copper hydroxide is redissolved as more concentrated ammonia solution is added to produce a dark blue copper compound called a “complex”.
gelatinous: a term meaning made with water. Because a gelatinous precipitate is mostly water, it is of a similar density to water and will float or lie suspended in the liquid.
◆ 2+ Copper
 Copper sulphate
and hydrogen sulphide A hydrogen sulphide solution is added to copper sulphate from a dropper. The result
is a precipitate of copper sulphide. Compare this precipitate to the copper hydroxide produced in
the demonstration on the opposite page.
EQUATION: Copper sulphate and hydrogen sulphide
Copper sulphate + hydrogen sulphide ➪ copper sulphide + sulphuric acid
CuSO4(aq) + H2S(aq)
Nitrogen
Oxygen
 A diagrammatic representation of the structure of the copper complex formed when excess ammonia solution is added to copper sulphate.
Hydrogen
➪ CuS(s) + H2SO4(aq)
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