Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
-----------------
hydrochloric acid : HCl
sodium hydroxide : NaOH
sulphuric acid : H2SO4
sodium persulfate : Na2S2O8
p-aminophenol HCl : NH2 C6H4 OH . HCl
Class:
------
elem=C
redox
Summary:
--------
When p-aminophenol is oxidized in acidic environment, then an intensely
colored compound is formed (indigo/purple). This compound is irreversibly
destroyed when the liquid is made alkaline.
Description:
------------
Add some p-aminophenol HCl and some sodium persulfate to dilute sulfuric
acid (appr. 7% by weight) and heat to appr. 60 C: An intense indigo/purple
compound is formed, the liquid becomes indigo/purple and remains clear.
Add an excess amount of a solution of NaOH: The liquid turns intense red/
brown, almost black.
Add an excess amount of HCl (10% by weight): Liquid remains dark red/brown.