Chemistry Reference
In-Depth Information
Material: Safety bowl, small crystallizing dish, glass tube (90 cm, sealed on
one end), pipette, small funnel (to fit into the opening of the glass tube),
folding ruler; mercury (T).
Procedure: The crystallizing dish in the safety bowl is to be filled with
mercury up to 3 cm. The glass tube - over the safety bowl - is to be totally
filled with mercury with the help of the funnel and the pipette, sealed with
the index finger and opened under mercury in the crystallizing dish. The
height of the metal column is to be measured with the ruler. The glass tube
is to be put into an inclined position and back into an upright position.
Observation: The mercury column sinks - depending on current air pressure -
to a height of 750-770 mm. In the inclined position the glass tube is totally
filled with mercury, the mercury column sinks to the metered value again in
the upright position.
Disposal: The mercury is to be put back into the container. If part of the
metal remains in the safety bowl it is to be picked up with the mercury
tongs. The glass tube is to be sealed with a stopper and stored in the cabinets
for further experiments.
E1.2.
Reaction of Copper Oxide and Hydrogen
Problem: This experiment exemplarily shows that elements can be obtained
from a compound: they are not “gone away” after their reaction. Redish-
brown, shiny copper can be obtained from the reaction of black copper
oxide with hydrogen - although copper cannot be seen in the black sub-
stance. It is possible to discuss “bearer of properties” versus “new
substances.” Simultaneous oxidation and reduction can be illustrated as
well as redox reactions in terms of oxygen transfer.
Material: Combustion tube with plug and outlet tube, porcelain ship, test
tube; black copper oxide (Xn), hydrogen (F
+
), cobalt chloride paper.
Procedure: Hydrogen is to be passed through the combustion tube, which
contains a porcelain ship filled with copper oxide. The hydrogen has to be
ignited on the outlet tube after a negative test of hydrogen-oxygen mixtures.
The copper oxide is to be heated with a burner. As soon as the reaction sets
in, recognizable by the formation of metallic copper, the burner can be
