Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
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ammonia : NH3
hydroxyl amine sulfate : (NH3OH)2 SO4
cupric chloride dihydrate : CuCl2 . 2H2O
ethanol : CH3CH2OH
Class:
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elem=Cu
coordination
redox
Summary:
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Copper (II) chloride is reduced by hydroxyl amine, when dissolved in
ethanol. First, the solution becomes much darker and apparently, a mixed
oxidation state complex of copper (I) and copper (II) is formed. Finally,
all copper (II) is reduced to copper (I).
This experiment is another example, which shows that copper (I) and copper
(II), when in solution at the same time, form a highly colored complex.
Description:
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Dissolve some CuCl2.2H2O in ethanol (denatured, 95%). The solid quickly
dissolves and the liquid becomes deep green.
Add a fairly large amount of (NH3OH)2SO4: The liquid becomes darker, when
it is shaken. The color also shifts from moss green to a more greyish
color. At a certain point, the liquid looks deep grey/green and still some
later, the liquid is very dark grey/green, almost black. After even
a longer time, the liquid becomes lighter again. Finally, the liquid is
very pale green/yellow.
Add a lot of water: The liquid at once becomes turbid white. Probably, this
white matter is precipitated CuCl.
Add some NH3 (5%): The white solid quickly dissolves, the liquid becomes
colorless. At the surface, which is in contact with air, the liquid becomes
deep blue.