Description of experiment
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Needed compounds:
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hydrochloric acid : HCl
sodium hydroxide : NaOH
p-aminophenol HCl : NH2 C6H4 OH . HCl
Class:
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elem=C
redox
Summary:
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P-aminophenol is quickly oxidized by oxygen from air in alkaline solution.
When acidified, the oxidation product becomes much lighter, but the original
compound is not restored again.
Description:
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Add some solid NaOH to a solution of p-aminophenol HCl: The liquid turns dark
brown. The reaction does not proceed as fast as with pyrogallol.
Add an excess amount of HCl (10% by weight): The liquid turns much lighter.
Besides this, a dark brown precipitate is formed, which remains floating
around through the liquid as large flakes.
Add much more water: The precipitate does not dissolve.