Page 8 - Curriculum Visions Dynamic Book

Reducing copper oxide
Copper is mainly found in the form of a black ore, copper oxide, or a brassy-coloured ore, copper sulphide. In both cases the metal has to be separated from its compound.
The demonstration on this page shows how copper can be extracted from its compound. The ore is copper oxide, a compound of copper and oxygen. To obtain pure copper the
oxygen has to be removed, using a process called reduction.
The reducing agent used here is carbon monoxide gas, which is colourless but inflammable. The reaction produces carbon dioxide gas, which is also colourless, but does not burn. So the key to watching this sequence is to look for where the flame appears and disappears. In this way you can tell which gas is in the tube!
The black copper oxide is heated with a Bunsen burner.
 The black copper oxide
is placed in a special glass tube with a small hole near the rounded end. At the start, the tube is full of air. This is swept away by pumping in carbon monoxide gas.
Carbon monoxide gas is passed in through this tube.
 The copper
oxide continues to
be reduced, and the oxygen combines with the carbon monoxide to form carbon dioxide. Carbon dioxide does not ignite, so the flame goes out.
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