Description of experiment
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Needed compounds:
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hydrochloric acid : HCl
hydroxyl amine sulfate : (NH3OH)2 SO4
vanadium pentoxide : V2O5
Class:
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elem=V,N
redox
Summary:
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Hydroxyl amine is capable of reducing vanadium (V) to vanadium (IV), but
further reduction is not possible with hydroxyl amine.
Description:
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Add an excess amount of HCl (10% by weight) to a mixture of hydroxyl amine
sulfate and vanadium pentoxide: The hydroxyl amine sulfate dissolves, the
vanadium pentoxide does not dissolve and remains yellow/brown. No visible
changes can be observed besides the dissolving of the hydroxyl amine sulfate.
Heat the liquid, with the solid vanadium pentoxide still at the bottom: The
vanadium pentoxide now quickly dissolves and a gas is developed at the solid
while it dissolves. When all of the solid vanadium pentoxide has dissolved,
the liquid has become sky blue (like a solution of a copper (II) salt).
Further boiling of the liquid does not result in any changes anymore.
Conclusion: Hydroxyl amine is capable of reducing vanadium (V) to the (IV)
state (blue vanadyl), but not further.