Description of experiment
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Needed compounds:
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potassium dichromate : K2Cr2O7
sulphuric acid : H2SO4
phenidone : C6H5 N N C(OH) CH2 CH2
Class:
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elem=C
redox
Summary:
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Phenidone can be oxidized by potassium dichromate and the oxidation
product appears to be a solid, dark brown compound, which does not
dissolve in water.
Description:
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Add some phenidone to a solution of K2Cr2O7 in H2SO4 (appr. 5% by weight):
The liquid becomes dark brown/green and turbid. When the liquid is shaken,
it looks as if a gas is evolved very slowly in the form of tiny bubbles.
However, these bubbles may also be the result of vigorous shaking and
sticking of bubbles in the dark brown solid.
Heat liquid to appr. 60 C: The liquid turns clear and its color becomes
less intense. The final color is brown.
Add more K2Cr2O7/H2SO4 solution: The liquid immediately turns dark brown
and turbid again. When the liquid is decanted from the glass, a layer of
brown material sticks to the glass. With a solution of NaOH the glass
can easily be cleaned, the brown stuff dissolves in the solution of NaOH.