Boron - only useful for ignitors?

[Mr Cool]

A few quick sums will show the following energy releases, per gram of fuel burning in excess oxygen:

WP: 24.3 kJ
Al: 30.9 kJ
C: 32.8 kJ
B: 57.5 kJ - <img border="0" title="" alt="[Eek!]" src="eek.gif" /> a full ten times that of a decent HE detonating!
(Beryllium beats it at 67.9 kJ, but would make clouds of toxic oxides and isn't commonly available)

And yet it seems to only be used in ignitors and as a green colourant :confused: .
Well, I think it deserves a bit of experimentation.

I intend to make some next time I have a bit of free time.
Na₂B₄O₇ + 2 HCl --&gt; H₂B₄O₇ + 2 NaCl
H₂B₄O₇ -(heat)-&gt; 2 B₂O₃ + H₂O, I think
B₂O₃ + 3 C -(heat)-&gt; 2 B + 3 CO

Should be easy, right? We'll see...
And it'll give me another reason to set up some sort of furnace for large batches if it works. I've been wanting a furnace for a while, but have never had enough reasons for me to actually decide to try and make one, so I always end up using the fire in the house!

Even if it isn't great for pyro things, it'd be a neat experiment. I'd try to make crystalline boron too, it's almost as hard as diamond and looks kinda pretty.

<a href="http://www.theodoregray.com/PeriodicTable/Samples/005.2.JPG" target="_blank">Crystalline Boron</a>

<small>[ January 14, 2003, 04:33 PM: Message edited by: Mr Cool ]</small>

[firebreether]

The problem is that saying that it has a lot of energy per unit mass fuel is misleading, because if you tried to do it in terms of total mass, then B would be less than something like Al. So for pyro comps, where it is the ox+fuel that matters, Al is a better choice(cheaper too) No doubt its always good to try new things though :D

[nbk2000]

There's a green mineral that's fairly cheap (I think it's called "beryl") that's mainly beryllium oxide. Crush it into a powder, reduce in H₂ atmo., and proceed form there. Or simply disperse the powder as is, since beryllium is very toxic.

I remember reading that boron "whiskers" are used in ceramic armor to prevent crack propagation.

[irish]

beryl is beryllium aluminium silicate, it's not toxic due to being practicly insoluble .
it's also the main commercial source of beryllium I will try to find out how they extract it .

[Flake2m]

Beryllium Oxide is not toxic, but it turns into Beryllium Hydroxide which is very toxic.

I went to a universtity open day last year and I saw a reaction with boron, the really wierd thing about it was the fact that the flame was completly green <img border="0" title="" alt="[Eek!]" src="eek.gif" /> .
Boron is also used in some weed killers aswell as in Ant killer, but the concerntration is quite small.

[THe_rEaL_dEaL]

Where I live they sell this stuff called Borax in the supermarket
From memory its like a compound containing boron
Something along the lines of boric acid
Not fully sure if its an acid but this is cause I'm too lazy to search cause I'm tired as shit
Its made by Hovea or Diggers I think
So if anyone can be fucked then they could find the MSDS or go down to the supermarket and check it out!!
This isnt a question so I'm not breaking the rules, only a statement with a sugestion. :cool:

[rikkitikkitavi]

well asbetos isnt toxic either, but not something you want to inhale.

BeO is worse...
gives you beryllosis (as asbetosis) and you can sign up for a lungtransplantation you you live that long.

soluble Be-compounds are toxic.

/rickard

[Mr Cool]

Damn, I hate it when you type out a reply and your computer fucks up and you lose it :(.

firebreether, yes you are right! I overlooked that fact [*hangs head in shame*]. I worked it all out and in a mixture with KClO3, Al just beats boron. But that was lost when my computer screwed up :(.

THe_rEaL_dEaL, borax is Na₂B₄O₇, which is what I intend to make it from.

[Sparky]

Mr. Cool, You don't need the intermediate steps, you can produce boron from borax, by heating it with carbon:
Na2B4O7 + 7C -&gt; 4B +2Na + 7CO

I don't know if the sodium metal will cause problems. Could be a bonus.

Boron oxide can of course be reduced by magnesium
B2O3 + 3Mg -&gt; 3MgO + 2B

The first samples of boron were made by reacting boric acid with potassium metal, but that is impractical for us.
In case you care, I got this quote from a Exploring Chemical Elements and their Compounds (I have found this book so useful you can watch for it appearing on the ftp, possibly next month):
"High-purity boron, on the order of 99.99% can be produced by the electrolysis of a molten mixture of potassium flouroborate and potassium chloride."

The same book has this reaction in it (This reaction must be heated):
Na2B4O7 + 2HCl + 5H2O -&gt; 2NaCl + 4H3B04

So maybe the first reaction you described would be impractical.

BTW borax comes as Na2B4O7.10H2O

[THe_rEaL_dEaL]

</font><blockquote><font size="1" face="Verdana, Arial, Helvetica">quote:</font><hr /><font size="2" face="Verdana, Arial, Helvetica"> you can produce boron from borax, by heating it with carbon:
Na2B4O7 + 7C -&gt; 4B +2Na + 7CO </font><hr /></blockquote><font size="2" face="Verdana, Arial, Helvetica">That equation seems right in theory but in reality the Na would form a salt (maby NACL or Na(CO₃)₂ wouldnt it?

I find it hard to accept that such a highly reactive element (reactive to air and water) in its pure form, would just exist in the presence of water or oxygen without causing a further reaction to create an Ionic salt of some sort.

I think I'm mostly correct.....? :)

I'm guessing that Boric Acid produced form Borax is further reacted to yield elemental Boron?

[Microtek]

I have been contemplating using boron as fuel in incendiaries. My resoning was that while Al does give a slightly better output per gram of thermite, boron is a lot harder and therefore probably easier to pulverise so it might be easier to prepare boron powder than Al powder. What I found when I did some calculations on the kinetics of discouraged me however so I never did the experiment.
I considered this method:

- Reacting borax with HCl in H2O to convert to boric acid and then reducing with carbon. 2H3BO3 + 3C --&gt; 2B + 3H2 + 3CO2.

This reaction require about 930 C to run assuming that deltaS standard and deltaH standard does not depend on temp ( which they probably will but hopefully not too much ).
There is a problem though; H3BO3 boils at a much lower temp, something like 180 C IIRC.
So, I considered this method instead:

- Burning borax and leaching out the Na2O with water to obtain B2O3 then 2B2O3 + 3C --&gt; 4B + 3CO2. B2O3 is not easily evaporated so that should take care of that problem. This rection requires a temp of more than 2500 C to be thermodynamically favored which is optimistic for any non-electric furnace.

Reduction of B2O3 with Mg is spontaneous ( except for activation energy ) at all temps so this can be done, just keep the amounts small as this is a thermite reaction itself. All in all I think it would be rather messy so I haven't tried it.

[Mr Cool]

I think I might use a mixture of Mg and C to reduce B₂O₃, in a crucible with a lid or something similar. That way, hopefully the energy released from the Mg + B₂O₃ "thermite" reaction will supply the energy needed for the C to reduce B₂O₃. MgO can then be removed with dilute HCl, and I expect any excess C would easily be removed by crushing it up and decanting from water (C having a low density will take longer to settle, so it could be poured off from the B as a suspension, maybe).
I'll let you know if it works when I try it, which will hopefully be this weekend. I might start off just using Mg as the reducing agent.

Edit: I don't think it will be this weekend, I'm feeling very hungover...
I hate tequilla.

<small>[ January 18, 2003, 08:08 AM: Message edited by: Mr Cool ]</small>