Description of experiment
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Needed compounds:
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sodium hydroxide : NaOH
glucose : CH2OH (CHOH)4 CHO
copper sulfate penta hydrate : CuSO4 . 5H2O
Class:
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elem=Cu
coordination
redox
Summary:
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Copper (II) builds a coordination complex with glucose in alkaline
environments. On heating, the glucose is oxidized by the copper (II)
and orange/red Cu2O precipitates.
Description:
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Add a solution of copper sulfate to a solution of glucose: No visible
changes. Liquid becomes pale blue.
Add some NaOH: The liquid turns dark blue and remains clear, even when
large amounts of NaOH are added. A coordination complex between copper (II)
and the glucose is built, which remains in solution.
Heat to appr. 60 C: The liquid changes color. Finally it becomes orange/red
and turbid. An orange precipitate is formed. This is copper (I) oxide.