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watson.fawkes
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If, by "above", you mean "next to".
Please, it is very fast to just look at the periodic table rather than making half-assertions so easily verified. Therefore, please make yourself a
bookmark. Here's the periodic table at Wikipedia.
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12AX7
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Si is even easier to purchase in powdered form, and aluminum can be alloyed with magnesium, forming an intermetallic much weaker than silicon.
Silicon will work fine as a reducing agent, simply because P is gaseous and nothing else in the reaction is.
Tim
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unome
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No, in above I mean it is capable of reducing things that are reportedly able to reduce phosphates - like Mg for example...
In terms of the periodic table itself, I hadn't actually looked so you have me there - fair cop
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Sedit
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Sooner or later I do highly wish to produce a retort able to perform these type of operations but I can not find a single reference of anyone online
doing such a thing. It there anyone here that has experiance with making a ceramic retort and suggestions on the shape and design on one.
The main issue that keeps popping up in my mind it the fact that these will be a one time use thing and it would kind of suck to put my heart into
sculpting a retort just to have it destroyed on the first, more then likely failed, attempt. Can anyone suggest any designs for one please.
Im considering also about making something that I could slip into one of the port holes on my kiln and this seems like it could be ideal considering
using cast iron pipes fitted correctly leading to a bucket of water at the base of the kiln. I worry about expansion with the heat though and wether
or not the threads will hold up under such stress because I really do not want phosphous vapors being expelled all over the place in my ceramic
workshop.
I have to go for now so ill post a few further questions a bit later.
~Sedit
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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blogfast25
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Garage Chemist:
Firstly referring to len1, there was no 'tone', it was merely a question. It was your experiments that inspired me to try the TCP (tertiary phosphate)
because it's amply available as bone ash.
It does surprise me these phosphates are reduced to phosphide and not to P [0] in the absence of silica...
But I can't even get the TCP thermite to light up properly. The last formulation was:
Ca3(PO4)2.............1 mol
CaSO4....................0.5 mol
Al...............................14/3 mol
It lit up (using KClO3/Al ignition mix) but then fizzled about half way.
Now I'll try and replicate your experiment, including silica. What is a good OTC source of Ca(PO3)2? I have none available right now.
Could monoammonium (dihydrogen)phosphate be converted to ammonium metaphosphate by heating?
NH4H2PO4 ---> NH4PO3 + H2O
Alternatively maybe displacing the ammonium in monoammonium (dihydrogen) phosphate by sodium with soda:
2 NH4H2PO4 + Na2CO3 ---> Na2H2PO4 + 2 NH3 + CO2 + H2O
[Edited on 7-12-2009 by blogfast25]
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blogfast25
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Later on today I'm gonna try and obtain NaH2PO4 by dry-distilling NH4H2PO4 with NaCl:
NH4H2PO4 (s) + NaCl (s) ---> NaH2PO4 (s) + NH4Cl (g)
And by further heating kill (hopefully) two birds with one stone:
NaH2PO4 (s) ---> NaPO3 (s) + H2O (g)
Then the metaphosphate will be mine (mwahahaha!)
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garage chemist
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You can just mix 1 mol monoammonium phosphate with 1 mol NaOH or 0,5 mol Na2CO3 in solution, and boil this down.
NaNH4HPO4 (microcosmic salt) decomposes to NaPO3 upon heating. Don't you know the analytical bead test with the magnesia stick or platinum wire and
this salt, for identifying heavy metals?
http://en.wikipedia.org/wiki/Microcosmic_salt
It is used just like Borax in the http://en.wikipedia.org/wiki/Borax_bead_test .
There's only a german page on this, no english one:
http://de.wikipedia.org/wiki/Phosphorsalzperle .
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blogfast25
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Which is what I what I did yesterday and finished off today (I used Na2CO3). I'd never heard of NaNH4HPO4 before but found it in Holleman's
'Anorganische Chemie' yesterday. I boiled down the solution and dried the product at 250 DC. It's a bit hard to extract from the pyrex jug, so I've
redissolved it and will recrystallize it more gently, tomorrow.
But the dry distillation of an equimolar mix of NH4H2PO4 and NaCl seems to be the most promising and mess-free way to convert my NH4H2PO4 into NaPO3
[(NaPO3)6, presumably?], IMHO.
I heated about 25 g of the mix in a thick stainless steel cup on medium heat on my lab gas cooker. It melted immediately, starts bubbling and thick
fumes of salmiak came off for about 1/2 hour. The mass had by then started to solidify somewhat (because of the higher MP of the metaphosphate?). I
cranked up the heat and give it another half hour, all gas evolution seemed to have stopped by then. After cooling I weighed the crucible again: the
yield of 13.6 g of product was within 2.5 w% of the stoichio amount (13.95 g) based on:
NH4H2PO4 + NaCl + heat ---> NaPO3 + NH3 + HCl + H2O
The product is a hard, crystalline mass, slightly green due to iron pick-up. It grinds down to a fine powder easily in a granite mortar.
It dissolves fairly easily in warm water, with some turbidity (iron phosphate?) and the solution (unknown concentration) is of pH = 2.4, a bit acidic
for my liking (but it would indicate there's no tertiary orthophosphate). On adding some pellets of NaOH and dissolving them, no smell of NH3 was
discernable, not even a whiff.
Added to egg white, the egg white solidifies (a typical test for meta phosphate, acc. Holleman). It does look like this product is NaPO3 (or its
hexamer).
So tomorrow, weather allowing, I will test:
2 NaPO3 + SiO2 + 10/3 Al ---> Na2SiO3 + 5/3 Al2O3 + 2 P
in thermite conditions.
Thanks also for the links...
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blogfast25
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I mixed up about 10 g of the stoichiom. metaphosphate/silica/aluminium powder mixture and put it in a small, thick walled stainless steel crucible.
Two attempts at lighting it as you would a thermite, in this case using KClO3/Al mix as initiating mixture and Mg ribbon as fuse, but no joy at all:
in both cases the mixture died after the initiating mixture was burned up.
Frustrated by then, I put the crucible on my gas cooker on medium-high heat direct propane flame and within a few minutes I saw clear phosphorescence
occur near the walls of the crucible: a fairly bright yellow-green glow, unmistakably phosphorescence because the experiment was carried out in the
dark, except for my torch light.
I called in to get my daughter to watch it but by the time I came back the crucible had caught a gentle fire: the phosphorus was being oxidised by air
and fumes of presumably P2O5 could be observed. By the end of the reaction the entire mass, by now presumably mainly sodium silicate and alumina, was
glowing a bright red. I'll hack into it later, when it's cooled down.
I think that also explains why lighting the mix as a thermite failed: I believe the reaction enthalpy is just borderline to make it self-sustaining.
This could be remedied with small amounts of heat-booster mix.
But the mixture as such is probably very suitable for producing phosphorus in a retort with external heating to get things going. I have just the
thing for that but I am clean out of aluminium powder right now...
The residue in the crucible is a hard, porous mass with a slightly unpleasant smell, reminiscent of the smell I get from dissolving reactive metals in
dilute mineral acids.
%%%%%%%%%
The product from the 'microcosmic salt' route has been further treated to be redissolving it, then boiling down to a sticky, syrupy consistency. That
was then transferred to a steel pan and heated on the gas cooker on high heat for a couple of hours. A hard, white-greyish crystalline mass results,
which was recovered and ground down.
An approx. 5 w% solution (turbid, though) of the product in water gave a pH of 4.3. The solution also solidifies egg white (denaturation of
albumin?).
Adding pellets of NaOH to the solution does not reveal any ammonia, not even the merest whiff.
Presumably this product is very similar to the one obtained via the NH4H2PO5 + NaCl route.
[Edited on 9-12-2009 by blogfast25]
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garage chemist
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Good work!
I assume you have read Strepta's method a few pages back (he attached it as a Word file)?
He obtained about 50% P4 yield by increasing the amount of aluminum above theoretical (although I would be careful with that, you don't want to bind
the P as phosphide again- perhaps increase the amount of SiO2 as well) and using pyro grade "black" aluminum powder.
I would also use diatomaceous earth (calcined before use) as the SiO2 source, as it's finely divided and very reactive (but not pure SiO2).
What kind of Al and SiO2 did you use?
Strepta also used CO2 as a protective atmosphere inside the test tube, but I would advise against that, as Al vigorously reacts with it, forming CO, C
and carbide. Perhaps that's why he had to increase the amount of Al?
N2 is also not an optimal choice (forms AlN).
If Ar is not available, H2 could perhaps be used.
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blogfast25
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Quote: Originally posted by garage chemist  | Good work!
I assume you have read Strepta's method a few pages back (he attached it as a Word file)?
He obtained about 50% P4 yield by increasing the amount of aluminum above theoretical (although I would be careful with that, you don't want to bind
the P as phosphide again- perhaps increase the amount of SiO2 as well) and using pyro grade "black" aluminum powder.
I would also use diatomaceous earth (calcined before use) as the SiO2 source, as it's finely divided and very reactive (but not pure SiO2).
What kind of Al and SiO2 did you use?
Strepta also used CO2 as a protective atmosphere inside the test tube, but I would advise against that, as Al vigorously reacts with it, forming CO, C
and carbide. Perhaps that's why he had to increase the amount of Al?
N2 is also not an optimal choice (forms AlN).
If Ar is not available, H2 could perhaps be used.
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Thanks!
I've just looked at Strepta's method and it's very neat but I'm not interested in such small amounts of P: if I'm gonna go to the trouble I want a
quantity I can at least comfortably continue experimentation with: halogenation perhaps.
I was thinking CO2, Ar or CO2/Ar mix. I'm surprised Al reacts with CO2 in those particular conditions, it sounds plausible he increased the Al level
to 'account' for what reacted with the CO2.
I'm not going anywhere near H2 with an open flame with a apparatus that's not certified gas tight..
I used a 200 mesh Al grade (not German black) and silica extracted from an old fashioned kitchen scouring product: the abrasive in there is merely
finely ground purified sand. Get rid of the soap by leaching and the silica is left behind. I'm guessing it's about 100 mesh. I've used it many times
before in SiO2/Al thermites. But I've also used finely ground desalinated and decarbonated beach sand in the past (for thermites).
As a retort I'm thinking about using an old SS teapot (500 ml) with bent copper tube soldered to the pouring spout (then the end of it submersed in
iced water or leading to a cold trap). Drill a hole in the side for Ar/CO2 entry and Bob's basically your uncle.
If the amount of mixture is sufficiently large compared to the amount of air in the retort an inert atmosphere might not even be necessary (Brand -
1669! and Scheele probably didn't use one either) because the P will become its own oxygen getter: the amount of oxygen in say 250 ml of air is only
about 0.002 mole of O2, equivalent to roughly about 0.06 gram of P. Of course there's the nitrogen: would it react with hot P?
I'm sure this has been discussed in this thread before but as an alternative (and very cheap) source of phosphate consider also bone ash: mainly
Ca3(PO4)2. React it with the equivalent amount of sulphuric acid and partially neutralise with soda or caustic soda to obtain NaH2PO4. Convert to
NaPO3.
[Edited on 10-12-2009 by blogfast25]
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Nicodem
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Maybe something too obvious, but shouldn't ammonium phosphate react with aluminium powder to give phosphorous at proper conditions? This would make
the use of silica unnecessary and the reaction should proceed at lower temperatures than with any of the sodium (poly)phosphates. The gasses forming
in the first stage of calcination (A; where aluminium polyphosphate forms) should purge the air from the reaction vessel protecting the mixture from
oxygen. Since the reaction enthalpy of the reduction stage (B) is considerably higher than with the analogous reaction of sodium phosphates, no
additional "acid" like SiO2 or Al2O3 should be necessary to smooth the reaction.
A: 3 (NH4)H2PO4 + Al => Al(PO3)3 + 3/2 H2 + 3 NH3 + 3 H2O (at < 300°C ?)
B: Al(PO3)3 + 5 Al => 3 P + 3 Al2O3 (at >900°C ?)
Or was this already tried and is not working?
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blogfast25
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That boils down to making the metaphosphate in situ, then subsequently reacting it with the excess Al. Provided the Al wouldn't react with the
orthophosphate (at modest temperatures that would be a reasonable assumption, crak up the heat to get the actual reduction started) then that's a real
possibility.
Not sure whether it's been tried yet. Strepta's set up would be suitable for testing it, without CO2 blanket...
It would yield a more useful byproduct too (alumina)...
But I can see a snake in the grass too: the acidic NH4H2PO4 is likely to react with Al to form Al tertiary orthophosphate, AlPO4 and H2.
The AlPO4 is not likey to convert to metaphosphate, apparently needed to obtain elemental P and not phosphide...
But that problem could be solved by using NaNH4HPO4 instead of NH4H2PO4...
[Edited on 10-12-2009 by blogfast25]
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Nicodem
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Or by simply adding silica or some other solid "acid" which brings us back to the industrial solution of the problem, the exact one that I thought
would be avoided.
However, I would not be so sure that AlPO4 forms at all. In the (NH4)H2PO4 + Al melt you always have an excess of the acid so no AlPO4 can form at the
beginning, only a melt of aluminium dihydrogen phosphate mixed with aluminium. The question is then if this melt dehydrates faster to the solid
mixture of aluminium metaphosphate + aluminium, before the aluminium gets corroded further, forming a mixture of AlPO4 + Al instead. I do not
know much about inorganic reactions and much less about reactions of metals in melts of salts, so I have no idea.
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entropy51
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| Quote: | | As a retort I'm thinking about using an old SS teapot (500 ml) with bent copper tube soldered to the pouring spout (then the end of it submersed in
iced water or leading to a cold trap). Drill a hole in the side for Ar/CO2 entry and Bob's basically your uncle. |
Sounds like a plan, but I hope you might be thinking of some kind of pressure relief valve or bursting disk, just in case.
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blogfast25
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| Quote: Originally posted by Nicodem | | However, I would not be so sure that AlPO4 forms at all. In the (NH4)H2PO4 + Al melt you always have an excess of the acid so no AlPO4 can form at the
beginning, only a melt of aluminium dihydrogen phosphate mixed with aluminium. The question is then if this melt dehydrates faster to the solid
mixture of aluminium metaphosphate + aluminium, before the aluminium gets corroded further, forming a mixture of AlPO4 + Al instead. I do not
know much about inorganic reactions and much less about reactions of metals in melts of salts, so I have no idea. |
Yes, I was a bit quick off the mark there. But in the melt:
Al + 3 NH4H2PO4 ---> Al(HPO4)3 + 3 H2 + 3 NH3
IS likely to proceed because NH4H2PO4 is quite acidic (a 1 M solution has a pH of about 3) and Al is very reactive of course. How the Al(HPO4)3 will
further fare I've no idea. Much depends on how the reactions proceed in time (in what order) and perhaps the heating rate. It's worth a shot.
| Quote: Originally posted by entropy51 | Sounds like a plan, but I hope you might be thinking of some kind of pressure relief valve or bursting disk, just in case.
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Pressure inside the retort should be quite small because the phosphorus evolves really quite gently and because I'd be using 1/2" copper pipe and a
short one at that. I'm more concerned with water being sucked up through the copper tube at the end of reaction, when the gasses start cooling and
under-pressure will be created. Some simple one way valve as a precaution to prevent steam explosions may be necessary. Otherwise a water-free cold
trap (or series of) may be safer still...
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pip
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What is holding back scale up? Isn't this method self controling or just at small scale? No one said that it can't scale up but no one mentioned doing
so either. (I had in mind 10 gram batches as a scale up to work towards)
Method for Preparation of Small Amounts of P4.
The attached is a description of a technique used to prepare small amounts (< .5g at a time) of white (yellow) phosphorus from sodium
hexametaphosphate (calgon). The chemistry for reduction of calgon using aluminum and silica was published by Franck more than a century ago and first
mentioned near the beginning of this thread by Polverone 6 years ago.
6NaPO3 + 10AI + 3Si02 = 3Na2Si03 + 5Al203 + 3P2
The reaction, properly implemented, is self -sustaining and initiates at temperatures which can be obtained with a lab (Meker) burner and conducted in
a test tube (18mmX150mm, pyrex), which can be re-used.
[Edited on 7-1-2010 by pip]
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Strepta
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pip: Of course it can be scaled up, albeit with somewhat different apparatus. I would suggest proceeding cautiously and incrementally; ie, do not mix
100 grams of reactants and confine them in a small space. Perhaps a length of pipe (or quartz tube if you wish to observe the reaction) with the
reactants laid in a linear train through the length of the pipe to help avoid a thermal runaway.
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blogfast25
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| Quote: Originally posted by Strepta | | pip: Of course it can be scaled up, albeit with somewhat different apparatus. I would suggest proceeding cautiously and incrementally; ie, do not mix
100 grams of reactants and confine them in a small space. Perhaps a length of pipe (or quartz tube if you wish to observe the reaction) with the
reactants laid in a linear train through the length of the pipe to help avoid a thermal runaway. |
I don't think there is much risk of a thermal runaway: thermochemical estimates of mine show that in adiabatic conditions (all heat retained) the
metaborate reduction reaction would reach about 800 C end-temperature and that is in line with observations by you, Garage Chemist and myself. 800 C
is much lower than a typical 'successful' thermite reaction and most of those run very contained too. If achieved temperature had been much higher
your test tube would of course have melted. It's exothermic all right but not terribly so. The 'slag' left behind was sintered, but hadn't melted
either...
Before any scale up I want to more or less replicate your test tube experiment but with some modifications. But the weather here is against me... 
[Edited on 7-1-2010 by blogfast25]
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pip
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Of course everyone here knows that scale ups can be dangerous and small increments are the safe thing to do. If not they do now. Seriously for those
like me who have minor chemistry knowledge but a vast willingness to learn and experiment never just multiply the "ingredients" to make the amount of
whatever you want, we're not baking cakes we are changing matter at one of its most basic levels. Best case senerio is it works, next best is it fails
to produce the product you want, and most likely it will blow in your face. P will kill you very painfully. I've had 3rd degree burns form gasoline
and faced with that again or a "P" mishap bring on the gas.
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pip
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what would the best choice of metal be for the reaction vessel? I don't want to accidentially want to use something that is going to react with the
phosphorus since it is at a high temp and all.
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Taoiseach
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@pip
I think you forgot to attach the calgon paper or at least I didn't see a link...
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blogfast25
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| Quote: Originally posted by pip | | what would the best choice of metal be for the reaction vessel? I don't want to accidentially want to use something that is going to react with the
phosphorus since it is at a high temp and all. |
Steel or copper would be fine.
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Myfanwy
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could phosphine and hydrogen peroxide yield some P4?
2PH3 + 3H2O2 -> 6H2O + 1/2 P4
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entropy51
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There's a book on phosphorus in the forum library. Why don't you read that and get back to us?
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