blip
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Messing around with superoxides
Back in chemistry class, we were shown double-replacement reactions with KI and Pb(NO<sub>3</sub> <sub>2</sub> both in aqueous solution and when solid, finely crushed crystals. I found it interesting that
it can be done in solid form and I wondered whether the same could be done with a lithium or sodium salt and potassium superoxide to make a lighter
superoxide after taking out the different potassium salt. Could NaO<sub>2</sub> or LiO<sub>2</sub> be stable after such a
thing, or would their electronegativities be too high to allow for it?
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Polverone
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interesting
I have never tried solid-state replacement reactions. I wouldn't expect to obtain the same results with an alkali superoxide and an alkali salt.
In solution you can prepare relatively pure salts (such as KClO4 from NaClO4 and KCl) but that's because of the great solubility differences. In
the solid state I don't see what could drive the exchange, or allow you to separate the mixture afterward.
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a_bab
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I read somewhere that these superoxides are formed at very high temperatures (via a plasma burner; around 30,000 degrees C needed). You can talk about
CaO2 for instance, but only at such temperatures.
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blip
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Equilibrium
I'm pretty sure equilibrium drives solid double-replacement reactions, so equal molar amounts of each substance mixed intimately would probably
yield the best results: near 1/4 NaO<sub>2</sub> or LiO<sub>2</sub>. You can't do double-replacement reactions with
superoxides like you can with NaClO<sub>4</sub> and KCl because KO<sub>2</sub> actually reacts with water. Could there be
some other solvent that could be used?
Ca(O<sub>2</sub><sub>2</sub>, eh... Maybe they
could be stable. I'm just aiming for a way to make them lighter.
Is there some magnetic polyatomic ion I could use for the separation of the non-superoxides?
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blip
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I found that NaO<sub>2</sub> is quite stable, whereas LiO<sub>2</sub> has only been prepared at 15K.
I now have a new question: Is there some way one could make KO<sub>3</sub> by reacting elemental potassium with ozone, perhaps in an
amalgam at some concentration? I was thinking that ozone might become more stable as an ion because then it won't need bond orders of 1.5
between each oxygen atom.
I apologize for the outrageous ideas. 
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I am a fish
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| Quote: | Originally posted by blip
...we were shown double-replacement reactions with KI and Pb(NO<sub>3</sub><sub>2</sub>... [as] solid, finely crushed crystals. I found it interesting that it can be done in solid form...
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Are you sure the reaction actually went to completion? I would think that only the surface of the grains would react. Therefore, the method would be
unsuitable for synthesis.
[Edited on 12-6-2003 by I am a fish]
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vulture
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Solid state reactions give very bad yields.
IIRC, KO3 can be made by bubbling O3 through cold concentrated (20N) KOH solution.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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blip
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NaO<sub>2</sub> can also be produced in high pressure combustion of the metal, as I should've expected (Section 3.1.2)
[Edited on 12-6-2003 by blip]
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Theoretic
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KO3 is also formed when passing O3 over dry, powdered KOH at -15C.
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