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Potassium oxide question

  1. Jan 8, 2006 #1
    Just what, exactly, is its melting point?

    I came across a ICSC website saying it decomposes at 350 degrees Celsius. Now how is that supposed to make sense, when it is itself a by-product of wood fires?
  2. jcsd
  3. Jan 8, 2006 #2


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    by decomposing they mean that it becomes its respective cation and anion gases. Ionic compounds may decompose before they are heated to melt or boil, you should review exactly how substances melt or boil with respect to the intermolecular attractions, kinetic energy, and the spatial aspects.
  4. Jan 10, 2006 #3


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    I've never come across something like this before (certainly not at temperatures as low as 350C). IMO, what you've described is (at least) highly unlikely, but then, that may just be something I'm unaware of. From my understanding of stuff like this, I would expect it took a lot more energy to "decompose" the ionic solid into a plasma than it would take to melt it. Do you have a reference I can look up ?
    Last edited: Jan 10, 2006
  5. Jan 10, 2006 #4


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    well you're the inorganic chemist, so I can't really argue with you in relevance to experimental concerns. I simply remember that some ionic compounds do not melt (or is it boil?), I got the impression that phase changes are a bit different with ionic compounds. By "decomposing" I figured it meant just that (in the original post), that instead of melting, the ionic compound becomes its respective ionic gases, as I've learned during my undergraduate years that this is what commonly happens; pure text book reference, I'll need to research upon the rigorous experimental details, specifically for potassium oxide and the in dynamic details undergoing, up till, its first stage in "decomposition."

    I suspect that at this point that the temperature for the plasma formation would be significantly higher than that required for adequate atomization, again the process is a bit unclear at the moment. Perhaps you can suggest. I'll need to do so when I find the time (the semester has just started for me).
  6. Jan 10, 2006 #5
    The real question here is: what is meant by "decomposing?" ...and under what conditions?

    In the open air, with plenty of additional oxygen and nitrogen, et. al? In a vacuum? In some inert atmosphere, if so, what? And, of course, what are the decomposition products? Potassium (II) oxide? (unlikely at 350C) Potassium Superoxide? (maybe) Potassium (0) and Oxygen gas? (not in the air, probably not at all) If not these, what?

    For what it is worth, both silver oxide and aluminum oxide thermally decompose to the elements, but neither of these elemental metals are as reactive as potassium.

    A relatively quick Google search showed potassium oxide as common product of the thermal decompositon of other things, but the only thing I could find about heating potassium oxide itself was "produces toxic gases."
    Last edited: Jan 10, 2006
  7. Jan 14, 2006 #6
    Does any potassium nitride form?

    The superoxide might make sense, but would it be a gas as described above?
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