Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
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sodium hydroxide : NaOH
vanadium pentoxide : V2O5
Class:
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elem=V
precipitation
Summary:
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Vanadium pentoxide can be dissolved in very concentrated solutions of NaOH
in considerable quantities. When such a solution is cooled down, then a
white crystalline solid separates from the liquid and the liquid completely
solidifies.
Description:
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Adda fairly large amount of V2O5 to a concentrated solution of NaOH and heat
until boiling: The solid quickly dissolves. The liquid does not become
completely clear. (This may also be due to impurities in the V2O5).
Let liquid cool down: In the liquid, white spots appear at random places.
These white spots slowly become larger and needle-like structures are formed,
pointing in many directions, starting from the white spots. Finally, the
complete liquid is filled by the needle-like crystal structures and the
liquid has become solid.
Add some water to the solidified liquid and shake: The solid quickly breaks
down in smaller particles and most of these particles dissolve.