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Author: Subject: Reduction of Silicon Dioxide with Lithium
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biggrin.gif posted on 25-8-2011 at 05:38
Reduction of Silicon Dioxide with Lithium


Ive been collecting elements for a while and ive got a few reductions i wanna do and the most reactive element i can find so far is lithium, is it possible to reduce Silicon Dioxide with Lithium?

4Li + SiO2 = 2Li2O + Si

Is this a good route to getting silicon? i have no other silicon salts to work with

Oh and would i be able to use crushed silica gel? ive been collecting quite a bit of them
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[*] posted on 25-8-2011 at 05:46


If your Silicone dioxide is fine enough mesh, it can be reduced with aluminum in a thermite. You may need a little Al/S mix to get it going. Search the forum, and there are also a few good Utube videos on the reduction of SiO<sub>2</sub> with aluminum.

Note, the resulting silicon will not be pure, but can be purified fairly easily IIRC.

Edit:spelling.

[Edited on 25-8-2011 by Bot0nist]




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[*] posted on 25-8-2011 at 05:46


I'd think that would work, but how were you going to mix the reactants together? Lithium won't last long in air before tarnishing.

I've done this through a thermite reaction. Here's my video of the process: http://www.youtube.com/watch?v=73YmP_JSrlU

The real reaction between Al and SiO2 is extremely difficult to get to work, so you add sulfur and extra aluminum as a booster, to provide extra heat to keep things going. I'm sure crushed silica gel would work better than the beach sand I used, since it's much more pure. That's one of the things I've wanted to try, but never got around to it. I did make pure SiO2 in another of my videos and that worked great in a thermite, so I imagine silica gel would be similar.
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[*] posted on 25-8-2011 at 05:52


ill just spread the SiO2 onto lithium foil and role it up tightly and ignite it in a tin can so that it can all react... lithium is way to soft to make a powder out of it, oh and MrHomeScientist, ive seen ur video 100's of times, love it... i don't have any source of aluminum or magnesium powder, that's why id rather use lithium and the way lithium burns, it reaches 1/2 the temperature of a thermite burning in open air... enclosed may be a different story
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[*] posted on 25-8-2011 at 06:00


Thanks! Glad to hear you enjoyed it :) You wouldn't happen to be toothpick93 would you? He was also asking me about arsenic trioxide recently.

Your plan with lithium sounds reasonable to me. I don't see why that wouldn't work. Give it a shot, I'm interested to hear the results! If it ends up not working, all you've wasted is a battery and some free silica gel :)
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[*] posted on 25-8-2011 at 06:05


And how about the old fashion reduction with carbon at high temp, I guess ridicilous temperatures.

SiO2 + 2 C → Si + 2 CO
My suspicion is right, its in the range of 1,900 degrees Celsius.
(according to wikipedia)
Would be cool to perform something like this at home, with a home built arc furnace this is possible.
Hot and scary :P

Another method suggested is molten salt electrolysis, this is could be difficult to do at home.



[Edited on 25-8-2011 by User]




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[*] posted on 25-8-2011 at 06:05


Yeah u guessed right, its me, how should i reward you? make a mini ground lampare this week end haha, yeah ill see what i can do and give it a shot on making the silicon, its actually a few battery, there is about 1 gram of lithium in a battery, so if you want a good yield a few grams would be needed, ill record and post what i get if i have time to do it and hope it works :D... so u looked at my other post on arsenic trioxide? yeah Google isnt very good for telling me what i want to here so instead i can ask on here and get pretty reasonable answers :)
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[*] posted on 25-8-2011 at 06:09


My only route to get a high temperature like that is to make a mini furnace with bricks, put some wood in the middle, poor napalm on top and light it up, napalm burns at really high temperatures and it may work if not with silicon production but will for other elemental production with coke
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[*] posted on 25-8-2011 at 06:12


You could try burning Mg in sand.




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[*] posted on 25-8-2011 at 06:12


Really?
What temperatures do you achieve with this method?





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[*] posted on 25-8-2011 at 06:15


SiO2 + 4 Li === > Si + 2 Li2O

… is thermodynamically feasible but only just. The Heat of Formation (HoF) of SiO2 is - 905 kJ/mol (NIST web book) and for Li2O the HoF is - 599 kJ/mol (NIST web book). So with Hess Law the Standard Heat of Reaction becomes:

ΔR<sub>R, 298 K</sub> = - (- 905) + 2 x (- 599) = - 293 kJ/mol

Assuming (almost certainly rightly) that entropic effects are small (ΔS ≈ 0) then:
ΔG = ΔH - TΔS ≈ ΔH, so with ΔG < 0 we know the reaction is thermodynamically feasible (but this says nothing about how to achieve this reaction).

- 293 kJ/mol is not a high value though and in all likelihood there won’t be enough heat to obtain the reaction products in the molten form. Instead you’d obtain Si powder, embedded in lithium oxide. Extracting the Si from there could be tricky: Li2O forms water soluble LiOH but strong alkalis attack Si vigorously.

As mentioned above, the standard method for making technical Si (Note: NOT solar or chip grade!) once used to be the reaction of sand (SiO2) with Al powder and sulphur. Here’s one I made earlier:

http://developing-your-web-presence.blogspot.com/2007/10/sil...

Al powder is quite easy to obtain.




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[*] posted on 25-8-2011 at 06:16


i just looked it up on Google and a few posts said about 1900 deg Celsius and others said over 2670 deg Celsius
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[*] posted on 25-8-2011 at 06:16


Quote: Originally posted by User  
Really?
What temperatures do you achieve with this method?



Not high enough: just google the insanely high MP of MgO (magnesia)...




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[*] posted on 25-8-2011 at 06:18


Quote: Originally posted by Chemistry Alchemist  
i just looked it up on Google and a few posts said about 1900 deg Celsius and others said over 2670 deg Celsius


What temperatures are you now talking about?




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[*] posted on 25-8-2011 at 06:19


I wouldn't want to waste good Lithium :) I'd imagine the thermite method with aluminum in a fine powder with a drop area for the heated results should get the job done.
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[*] posted on 25-8-2011 at 06:21


Quote: Originally posted by blogfast25  
Quote: Originally posted by Chemistry Alchemist  
i just looked it up on Google and a few posts said about 1900 deg Celsius and others said over 2670 deg Celsius


What temperatures are you now talking about?


Burning Napalm
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[*] posted on 25-8-2011 at 06:22


Quote: Originally posted by Wizzard  
I wouldn't want to waste good Lithium :) I'd imagine the thermite method with aluminum in a fine powder with a drop area for the heated results should get the job done.


I don't have any Aluminum or magnesium powder unfortunately, that's why i have to use lithium for it, and anyways once i get a job, i can just buy more battery's, dismantle them and bam... lithium
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[*] posted on 25-8-2011 at 06:24


Quote: Originally posted by Chemistry Alchemist  


Burning Napalm


Oh dear, we've got a wannabe commedian on our hands. Considering the sort of nonsense and other fallacies you've been spouting here so far, I'd suggest you try and put your 'serious hat' on, okay?




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[*] posted on 25-8-2011 at 06:25


I am not sure of your location, but Mg and Al powder is easy to source online, and much, much cheaper than buying and destructing lithium batteries.

[Edited on 25-8-2011 by Bot0nist]




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[*] posted on 25-8-2011 at 06:26


Quote: Originally posted by blogfast25  
Quote: Originally posted by Chemistry Alchemist  


Burning Napalm


Oh dear, we've got a wannabe commedian on our hands. Considering the sort of nonsense and other fallacies you've been spouting here so far, I'd suggest you try and put your 'serious hat' on, okay?


what do u mean by that?
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[*] posted on 25-8-2011 at 06:31


Quote: Originally posted by Chemistry Alchemist  
what do u mean by that?


Read it again: it's not rocket science.




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[*] posted on 25-8-2011 at 06:37


Are you talking about gelled gasoline with Styrofoam aka 'kewl napalm'? Probably not the best way to reach high temps in a homemade furnace. Why not a carbon fire with a bellows or O<sub>2</sub> injection? Would that be hot enough with good insulation I wonder



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[*] posted on 25-8-2011 at 06:39


yeah thats the napalm im talking about, i dont have the right tools to make a proper furnace, thats why i suggested the napalm... worst part is, napalm burns and produces a black soot residue and people may be asking questions to why black smoke is coming from my back yard
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[*] posted on 25-8-2011 at 06:44


Quote: Originally posted by Chemistry Alchemist  
yeah thats the napalm im talking about, i dont have the right tools to make a proper furnace, thats why i suggested the napalm... worst part is, napalm burns and produces a black soot residue and people may be asking questions to why black smoke is coming from my back yard


It's obvious you don't really know what you're talking about... wood fires don't even melt copper on the best of days and you start thinking you can use flaamethrower fuel? ;)

Now it's usually easier to achieve such high temperatures with an electric arc. If you want to purify silicon in small quantities like a gram or so for fun you could just try to use graphite electrodes and a car battery.




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[*] posted on 25-8-2011 at 06:44


"worst part is, napalm burns and produces a black soot residue and people may be asking questions to why black smoke is coming from my back yard"

That's not the worst part.

[Edited on 25-8-2011 by Bot0nist]




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