Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
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nitric acid : HNO3
copper : Cu
ligroin : C7H16
Class:
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elem=C;N
redox
Summary:
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Alkanes do not react strongly with NO2. Some NO2 dissolves in them.
Description:
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Pour some ligroin (a mixture of lower alkanes with 6, 7 or 8 C-atoms)
on HNO3 (appr. 50% by weight): A two-layer system is formed. The ligroin-
layer is on top of the aqueous layer. The ligroin-layer becomes slightly
turbid.
Add some copper metal: The metal sinks through the ligroin layer into the
nitric acid, where it dissolves and a gas is evolved. The gas bubbles through
the ligroin layer partially. The air above the ligroin layer turns pale
brown, the ligroin layer itself becomes yellow/brown. Apparently NO2
dissolves to some extent in ligroin, but it does not react (at least not
quickly and completely) with it. A colorless gas bubbles through the
ligroin. This is NO, formed at the oxidation of copper and does not
dissolve in ligroin.