Description of experiment
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Needed compounds:
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sodium hydroxide : NaOH
trichloroethene : CHCl CCl2
pyrogallol : C6H3 (OH)3
Class:
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elem=C
redox
Summary:
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Pyrogallol does not dissolve in trichloroethene very well, but some of it
does dissolve.
Description:
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Add some solid pyrogallol to some CHClCCl2: The solid does not dissolve (at
least no visible amount is dissolved).
Carefully pour a solution of NaOH on top of the tri-layer: The aqueous layer
keeps floating on top of the tri-layer. The aqueous layer turns dark brown,
the tri layer remains colorless. All pyrogallol dissolves, without shaking.
Apparently pyrogallol does dissolve in trichlorethene, but only a small
amount. The aqueous layer extracts pyrogallol from the tri-leyer, making
room for new pyrogallol to be dissolved in the tri-layer. In this way, all
pyrogallol can be dissolved in the trichloroethene.
After all pyrogallol is dissolved, shake vigorously: The tri-layer settles
at the bottom again and is almost colorless, the aqueous layer is dark brown.
The surface of separation between the tri-layer and the aqueous layer is
perfectly flat, it is not convex nor concave.