Description of experiment
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Needed compounds:
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sodium hydroxide : NaOH
EDTA tetra sodium : (NaOOC CH2)2 N CH2 CH2 N (CH2 COONa)2
copper sulfate penta hydrate : CuSO4 . 5H2O
Class:
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elem=Cu
coordination
Summary:
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EDTA builds a coordination complex with copper (II). This complex has a
color, resembling the color of simple hydrated copper (II), but it is
much more intense and it has a slightly more cyan-like color.
This complex is not stable in strongly alkaline environments.
Description:
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Add a solution of EDTA tetra sodium to a dilute solution of copper sulfate:
Strong intensification of the color of the liquid and a slight shift towards
cyan. The color of the liquid is bright blue/cyan and the liquid is slightly
turbid.
Add a fairly large amount of a solution of NaOH: The liquid becomes turbid,
a pale blue precipitate is formed, which floats around in the liquid in the
form of little flakes.