Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
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zinc : Zn
dimethyl sulfoxide : (CH3)2SO
niobium pentachloride : NbCl5
Class:
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elem=Nb
redox
coordination
Summary:
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Niobium pentachloride dissolves in DMSO, and slowly reacts with it, giving a
really foul smelling compound.
Description:
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Add some solid NbCl5 to some DMSO: The solid slowly dissolves and the liquid
becomes gold/yellow and clear. No violent reaction can be observed, as when
NbCl5 is added to water, it simply dissolves. Dissolving at first goes quite
fast, but it become more and more difficult. The yellow compound in solution,
however, quickly disappears. The solution becomes colorless within a few
minutes. The liquid also obtains a not so strong, but really foul smell.
There is no pungent smell of HCl (the DMSO, used for this experiment is
99.9% pure and almost free of water).
Could it be, that DMSO reacts with NbCl5, giving NbOCl3 and (CH3)2SCl2?
Add some zinc to the colorless and clear solution in DMSO: There is formation
of some turbidity, and the liquid becomes brown. The turbidity may be due to
formation of very fine bubbles of gas.
Add some water: The zinc now dissolves somewhat faster and a gas is produced.
This gas most likely is hydrogen gas. The liquid remains brown. The foul
smell persists, also after adding the water.