Naked Science Forum
Non Life Sciences => Chemistry => Topic started by: tommya300 on 29/08/2010 21:25:30
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Why is it or why isn't it.
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It is strongly paramagnetic because (unusually) oxygen has a ground state with unpaired electrons.
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Yes- the University of Nottingham did a demonstration of this on their open day with a test tube of liquid oxygen hanging from a string and a magnet [:)]
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Can oxygen exhibit this property in the other states of matter?
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Yes, it's also paramagnetic as a solid and a gas.
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Note that (molecular) oxygen is magnetic in the sense that iron is magnetic - it is attracted to a magnet.
It is not magnetic in the sense of being, in the bulk, a magnet in its own right... a vial of liquid oxygen won't attract a lump of iron to itself.
This is because in a paramagnetic substance such as O2, although the individual molecules may be considered as a bit like little magnets an overall magnetic field is generated only if there is an overall tendency for those magnets to line up in a particular direction. Soft iron can be magnetised (turned into a permanent magnet) by the presence of a magnetic field because those little magnets can be forced to line up and, once lined up, will remain aligned. Because oxygen's a liquid all the molecules are continually tumbling about and don't stay aligned.
It's possible (I don't know and haven't looked it up) that if liquid oxygen were cooled to a solid in a magnetic field a permanent magnet might result... but in any case as BC says the solid would be attracted to a magnetic field.
Although gaseous oxygen is attracted to magnets, the magnetic force per molecule wouldn't be strong enough to detectably enrich the oxygen in the atmosphere around a magnet in the face of normal air circulation, so it's not an important effect.