CrEaTiVePyroScience
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Alkali metals with hydrogen peroxide
So I was observing wat happend with some lithium and water and it wasn't that spectacular. Which I actually already knew.
But my question is, what would happend if you would add an alkali metal to hydrogen peroxide (35%). Will this change the reaction? Ive tried to google
and check youtube but couldn't find anyone who have tried it before. Maybe anyone here can predict what possibly will hapend?
When lithium comes in contact with water it doesn't catches fire automaticly you have to ingite it then, but maybe it will ignite at it's own due to
the oxygen? I really don't know maybe anyone does?
[Edited on 21-4-2012 by CrEaTiVePyroScience]
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weiming1998
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Quote: Originally posted by CrEaTiVePyroScience  | So I was observing wat happend with some lithium and water and it wasn't that spectacular. Which I actually already knew.
But my question is, what would happend if you would add an alkali metal to hydrogen peroxide (35%). Will this change the reaction? Ive tried to google
and check youtube but couldn't find anyone who have tried it before. Maybe anyone here can predict what possibly will hapend?
When lithium comes in contact with water it doesn't catches fire automaticly you have to ingite it then, but maybe it will ignite at it's own due to
the oxygen? I really don't know maybe anyone does?
[Edited on 21-4-2012 by CrEaTiVePyroScience] |
If you try and react lithium with H2O2, something like this will happen:
First Li reacts with H2O2, but probably not to Li2O2, because this is in aqueous solution, and H2O2 is not basic enough to have both H+ deprotonated
in aqueous solution (H2O will deprotonate to OH- instead). So I can think of two hypothetical reactions
1st: 2Li+2H2O2===>2LiOOH+H2, forming a hydroxyperoxide(?) compound, which I can find no info about.
2nd: 2Li+H2O2===>Li2O2+H2, but then Li2O2+2H2O==>2LiOH+H2O2. No H2O2 would be consumed.
As H2O2 has similar pH(slightly more acidic) as H2O, the reaction probably gives out similar amounts of energy. The amount of oxygen does not change
the autoignition temperature, so no ignition probably comes from either of these above 2 circumstances.
But let's consider a third hypothetical reaction:
2Li+H2O2===>Li2O+H2O. The H2O2 oxidizes the lithium. Then ignition is far more likely, as this gives out 353kj/mol more energy than the reaction of
O2 and Li, not counting the energy produced by the hydration of Li2O. Still the H2O in the solution acts as a cooling bath, stopping the reaction from
becoming self-sustaining. But could the heat produced pass through the lithium and ignite the rest of it? There's so much to think about, so much to
calculate, so I suppose the best thing to do, is to find out!
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CrEaTiVePyroScience
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Really thanks I will defently do some tests soon and let you guys know. I haven't found anything about that reaction looks like almost no one has done
it before.
If anyone got other hypotheses would be glad to hear!
And how about increasing or decreasing the ph of the solution you put the lithium in, will that increase/decrease the amount of energy released (in a
shorter time) ?
[Edited on 21-4-2012 by CrEaTiVePyroScience]
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weiming1998
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| Quote: Originally posted by CrEaTiVePyroScience | Really thanks I will defently do some tests soon and let you guys know. I haven't found anything about that reaction looks like almost no one has done
it before.
If anyone got other hypotheses would be glad to hear!
And how about increasing or decreasing the ph of the solution you put the lithium in, will that increase/decrease the amount of energy released (in a
shorter time) ?
[Edited on 21-4-2012 by CrEaTiVePyroScience] |
A pH of 7 indicates that for every mole of water, 10^-7 moles of H3O+ and OH- is spontaneously formed at any given time. When you react lithium with
water, the lithium reacts like this: 2Li+2H3O+===>Li(+)+2H2O+H2 instead of directly reacting with water. There would be now a solution of Li+ and
an increase in concentration of OH- Now let's suppose we increase the H3O+ concentration. The lithium will certainly react faster, but because it is
still in ion form in water, there would be no energy differences. It just appears to be more energetic (and will heat up more) because the reaction is
faster, so that there would be less time for the energy to dissipate during the reaction. A decrease of H3O+ will result in a slower reaction,
resulting in more time for energy to dissipate and thus the reaction appears less energetic. But the total amount of energy generated will not change
at all.
Now, if you use concentrated acids instead of an aqueous solution, then it's a different story.
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Adas
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Li + H2O2 ----> 2 LiOH
Rest In Pieces!
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AndersHoveland
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The reaction of elemental sodium with a solution of 30 percent H2O2 is less spectacular than water.
Apparently most of the fire and explosion comes from the ignition of the hydrogen which is generated. When H2O2 is used, the sodium mostly gets
oxidized, and much less hydrogen is produced.
If one was throwing big pieces (1 kilo) into water, this contrast could possibly be different. When larger quantities of reactants are used, the
direct reaction between the sodium and water essentially becomes explosive, and any hydrogen-air ignition would be expected to become less important
relative to the Na-H2O or Na-H2O2 reaction. My unsubstantiated guess would be that a K-Na liquid alloy would react with H2O2 much more explosively
than with water.
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CrEaTiVePyroScience
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Thanks everyone for the hypotheses and this looks like some "undiscovered" territory I will do several tests and make videos and photos about it.
Doing multiple tests on alkali metals (mostly lithium) and observe how they react with different acids, bases, & hydrogen peroxide. Will let you
guys know my work within two weeks.
Will make a video about it that will also be posted on my youtubechannel.
-CrEaTiVePyroScience
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AndersHoveland
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I actually saw a video of sodium being dropped into 50% H2O2 compared to water. It was surprising that the 50% H2O2 did not really seem to do much
compared to the plain water.
I have also made the interesting observation that calcium acetylide, CaC2, seems to be essentially unreactive with alocohol. And the reaction is very
slow in solutions of 90% alcohol.
http://www.youtube.com/watch?v=BWGx0FsmW9M
[Edited on 21-4-2012 by AndersHoveland]
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DerAlte
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Why don't you try it instead of speculating?
Der Alte
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CrEaTiVePyroScience
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@DerAlte
I said that I am trying it (check my post before..)
But before I was going try it I wanted to make sure there wouldn't be any dangerous explosion or dangerous reaction happening. So couldn't find
anything on google about it and no one looks to be sure about it but no one really expects something special to happen, anyway I will try first on
small scale (5ml beaker with few 100mgs of lithium) and scale it up. Will let post result on this forum
[Edited on 22-4-2012 by CrEaTiVePyroScience]
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