Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
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sulphuric acid : H2SO4
potassium tetraperoxochromate (V) : K3CrO8
Class:
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elem=Cr
redox
Summary:
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Potassium tetraperoxochromate slowly dissolves in concentrated sulphuric
acid, it quickly dissolves (and decomposes) in dilute acid.
Description:
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Add some solid K3CrO8 to some concentrated H2SO4 (appr. 96%): Very slow
evolution of a gas (probably oxygen) and the crystals hardly dissolve.
Add some water (appr. twice the volume of water is added as the volume of
H2SO4): Violent reaction (boiling?), the crystals have dissolved almost
instantaneously and the liquid is light green after the reaction and very
hot (reaction between water and H2SO4).
Add some solid K3CrO8: The crystals almost instantaneously dissolve in
the acidic liquid with the evolution of a gas. After the reaction, the
liquid is green (a well known color of trivalent chromium).