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Author: Subject: Preparation of elemental phosphorus
blogfast25
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Seems to me you didn't produce much P and that some of it got converted to phosphine.

Another theory could be that the orthophosphate, in the absence of silica, was reduced to phosphide [-III], rather than to elemental phosphorus:

AlPO4 + 2 C ---> AlP (or similar) + 2 CO2

AlP + 3 H2O ---> Al(OH)3 + PH3

You seem rather hell bent on trying a very elegant set up on methods (mixtures) that seem unproven...

DO try Strepta's metaphosphate + silica + Al: salvation lies therein!
Magpie
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What does this look like?

 Quote: Originally posted by Magpie Today I made a small amount of P according to the following reaction: 6NaPO3 + 10Al + 3SiO2 --> 3Na2SiO3 + 5Al2O3 + 6P [Edited on 6-3-2010 by Magpie]

The single most important condition for a successful synthesis is good mixing - Nicodem
Strepta
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@blogfast: Magpie knows full well about the reduction of metaphosphates. He and I are exploring different chemistries for the lab prep of P4. The following excerpt is from Industrial and Engineering Chemistry, V 21, No 11, p 1130, originally posted by SC_Wack upthread several weeks ago:

“To determine whether addition of silica to the charge
increases the rate of reduction of aluminum phosphate,
10-gram mixtures containing equal weights of aluminum
phosphate and carbon and sufficient silica to give a 1 : 1 mol
ratio of alumina to silica were heated for 1 hour at 1050"
and at 1100" C. The percentages of phosphorus volatilized
were 5.3 and 73.7, respectively, showing that silica has very
little, if any, effect in accelerating the reduction of aluminum
phosphate at these temperatures.”

The importance of silica in the reduction of tricalcium phosphate is acknowledged and contrasted with this result. One result is that the reactants do not fuse together as they do with the metaphosphate/SiO2/Al reaction, making P4 recovery and cleanup much more straightforward.
blogfast25
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Touché!
Melgar
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I made elemental phosphorus today. I was surprised how easy it was. I got a 6-inch long, 1-inch wide alumina tube off ebay for $20, and a roll of nichrome wire for like$5. I wound about ten feet of nichrome wire around the tube. Then I lined a big tomato can with fiberglass insulation, then made an inner layer of rockwool purchased from a hydroponics store. I nested the tube inside that, and packed both ends with fireclay plugs. I had a stainless steel tube coming out of the top plug and into a beaker of water. I hooked up alligator clips to the wire, then plugged the whole thing directly into the wall. A bad idea if you don't know what you're doing, but I do. I had it hooked up to one of those kill-a-watt things so I could see how much power I was drawing, which turned out to be like 500 watts.

The next step was packing it with reactants. I mixed ground up charcoal, phosphate fertilizer, and powdered fiberglass together and filled the tube with that.

Then I fired it up again with the reactants in it. At first a bunch of smoke came out. Then that stopped. Then some other gas came out, then that stopped. Then a bunch of white smoke came out, which caught fire as soon as the bubbles came out of the water. The bursts of flame continued for a while, then stopped. This was all done outside, btw. So I unplugged the device and gave it some time to cool off. Then I went and looked at the beaker. It had a white scum on top, that when I swirled it around, a bunch of flecks fell to the bottom. It also had that matches/fireworks phosphorus smell to it. I didn't take a huge whiff of it, but I couldn't help noticing that.

I was surprised at how simple it was, especially considering the lack of firsthand accounts when it comes to preparing elemental phosphorus.

[Edited on 4/1/10 by Melgar]
halogenstruck
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its easier if u use microwave.
i mixed equal weights of charcoal powder and 85% H3PO4 very well then put in test tube and cotton wool and then salt layer==>microwave for 4 minutes.
a gas comes out which burns and at the end u can see green phosphorescence of P inside tube and if u put end of tube in water upside down u see it stops.
red spots in cotton wool and salt is red phosphorus
i did not have glass wool-glass tube,... to separate P.
it smells also like white P ,garlic.
huge fumes of P4O10 comes almost immediately after turning microwave on
halogenstruck
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P preparation in microwave from H3PO4/C

Attachment: P prep in microwave.pdf (1.3MB)
halogenstruck
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I MIXED 100% extra mole/mole charcoal powder and 85% H3PO4 then i put it at the bottom of a test tube,covered by a thin glass wool layer,upside-down inside a cup of water.
in first 4 or 5 minute,a lot of gas was evolved.but 16min was necessary to allow P ring comes down the tube.
because P releases very fast but immediately because of heat turns to red/violet P.
red/violet P melting point or sublimation temperature based on wikipedia is between 416 to 590 °C.
therefore it does not come out easily as mixture does not warm very well and needs lengthy heating in microwave to get warm enough all the area inside.
as another idea,its not a bad way just to heat in microwave for 5min then using the black mixture as a phosphorus containing mixture: Red P/active C in reactions
result was yellow P containing little Red P,waxy.
white fume in air due to auto-oxidation in air,greenish phosphorescence[chemiluminescence] especially when boiling with water
starting with 1.5g C resultin just a little bit.
taking out P from mixture is not easy.even in us patent related to microwave reduction,they calculated yield based on weight reduction
[Edited on 8-4-2010 by halogenstruck]

[Edited on 8-4-2010 by halogenstruck]
condennnsa
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 Quote: Originally posted by Melgar It also had that matches/fireworks phosphorus smell to it. I didn't take a huge whiff of it, but I couldn't help noticing that. [Edited on 4/1/10 by Melgar]

Fireworks contain NO phosphorous. I think you confuse the smell of P2O5 with that of sulfur dioxide. SO2 is the smell of matches and fireworks. The only pyrotechnic composition containing phosphorous is armstrong's mixture (KClO3/P) and it is extremely sensitive and never used. Matches however do rely on phosphorous, but only at the instant when they are lit, the KClO3 from the match head and the red phosphorous from the striking surface react to give enough heat to ignite the rest of the sulfur/KClO3 mixture in the matchhead.
Jimmymajesty
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I also made some phosporous from the strike surface of a matchbook, scaped off the red P with a pocket knife, then took a small glass tube sealed at one end, and poured the red P inside it, then I filled up the small tube with butane and heated with an open flame, the red P immediately turned into white.. It took about a second!

I went into a dark room and shook the white P drop out of the tube, it immediately started to glow upon contact with air It is a really nice experiement and easily carried out by anyone @ home.
entropy51
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 Quote: Originally posted by Jimmymajesty I also made some phosporous from the strike surface of a matchbook, scaped off the red P with a pocket knife, then took a small glass tube sealed at one end, and poured the red P inside it, then I filled up the small tube with butane and heated with an open flame, the red P immediately turned into white.....It is a really nice experiement and easily carried out by anyone @ home.

I don't get it. You think white P is a good home experiment, but you just said:
 Quote: Originally posted by Jimmymajesty I saw a video on youtube (elementary videos IIRC) in which the dude handled uranium and its salts, but in a glove box to avoid poisoning himself to death.. Who wants to bring chems like this to his home?
It is much easier to become poisoned by the fumes of white P than by U.
Jimmymajesty
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I also do not get it what kind of illness can you get from H3PO4 possibly P2O5?
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 Quote: Originally posted by Jimmymajesty I also do not get it what kind of illness can you get from H3PO4 possibly P2O5?

 Quote: Phosphorus pentoxide is not flammable. It reacts vigorously with water and water-containing substances like wood or cotton, liberates much heat and may even cause fire. It is corrosive to metal and is very irritating – may cause severe burn to the eye, skin, mucous membrane, and respiratory tract even at concentrations as low as 1 mg/m3.

From wikipedia.
not_important
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 Quote: Originally posted by Jimmymajesty I also do not get it what kind of illness can you get from H3PO4 possibly P2O5?

It's not the oxidation products, it's actual vapour from the white phosphorous - P4 molecules.

Do a Web search on the term "phossy jaw", you'll like the pictures.

Anders Hoveland
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If the elemental phosphorous is being made just to obtain P2O5 (or P4O10) as a dehydrating agent, I have a suggestion that can avoid the need for distillation.
2Na3PO4 + 12S --> 3Na2S + P2S5 + 4SO2gas
obviously this is fused and heated together to drive off the SO2.

The Phosphorus pentasulfide could be used to make H2S, which otherwise would require metal powder to make.
P4S10 + 16 H2O → 4 H3PO4 + 10 H2S (from wikipedia)
Or the P2S5 could slowly burned, giving off SO2, and the P4O10 smoke would quickly crystallize after cooling.

Acetone reacts with P2S5 to make the unstable thioketone, which is extremely stinky, far more so than H2S. You can cause a small town to be evacuated with this reaction.

[Edited on 27-6-2010 by Anders Hoveland]
blogfast25
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Have you tried this in practice? This might take some serious temperatures, possibly above the BP of S...

Also I'm not convinced that ΔG < 0 for the first reaction. Of course if SO2 starts coming off it would drive the equilibrium to the right...
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I am interested in getting red phosphorus from matchboxes. What is the best way of doing it to make it almost pure?
Sedit
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Locate a forum called wetdreams and then get to reading!

Knowledge is useless to useless people...

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JohnWW
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Red P is very soluble in CS2. If you can get that solvent, try it. It is also soluble in liquid NH3. (I am not sure about ".88" NH3 solution, though).

Or alternatively, you could find a solvent that dissolves the binder (I am not sure what it is - it could be ordinary water-soluble paste) used to glue the pyrophoric abrasive mixture to the matchboxes, leaving the red P and abrasive unchanged as solids. But then, the problem would be how to separate the red P from the abrasive.

[Edited on 2-7-10 by JohnWW]
Picric-A
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JohnWW- I thought it was white P that was very soluble in CS2, not red P... could be both i suppose...

Try soaking the matchboxes in acetone, then scraping the red P off. that is as pure as you will get it uness you then sublime the red P, makign white P then convert that to pure red P.
woelen

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 Quote: Originally posted by JohnWW Red P is very soluble in CS2. If you can get that solvent, try it. It is also soluble in liquid NH3. (I am not sure about ".88" NH3 solution, though).
There is no solvent for red P at all which does not destroy the red P. If it does dissolve in some solvent (e.g. a mix of HNO3 and HCl does the job when heated), then it is oxidized to (usually) H3PO4. Indeed, it is white P which dissolves very well in CS2. The resulting liquid is extremely dangerous, it is self-inflaming in air, because the CS2 quickly evaporates and finely divided white P remains behind.

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I will try to soak matchboxes in acetone to remove glue at least. What are other things that are on matchboxes?
woelen

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The brown material usually consists of a mix of red P, fine glass/silica particles to make it more abrasive, some glue and IIRC also some antimony sulfide (Sb2S3) in order to ease ignition. The amount of red P is only a few tens of percent, the rest is useless crap and it is not easy to separate from the red P. There is no solvent for red P, nor is there for the glass/silica and separation will be very difficult. You also need a LOT of match boxes in order to obtain decent amounts. One match box contains just a few mg of red P.

If you are in the EU, then just buy red P, it's not that expensive. If you are in the USA then try to find another area of chemistry which is interesting for you...

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Anders Hoveland
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Probably using boric oxide on a sodium pyrophospate would allow operation at a much lower temperature than silica and calcium phospate. All I want is the P4O10 for drying HClO4 and HNO3, so there is no need to reduce the oxide with charcoal.
mario840
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Hi guys !

You tell that PCl3 cannot be make from red phosphorus ?? So what about method this :

We make a little PCl3 first from say 10 g of WHITE phosphorus , so we have about 37 ml of pure PCl3 then we add this PCl3 to a red phoshporus in the flask and then GAS with chlorine ?? this may work ???
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 Sciencemadness Discussion Board » Fundamentals » Chemistry in General » Preparation of elemental phosphorus Select A Forum Fundamentals   » Chemistry in General   » Organic Chemistry   » Reagents and Apparatus Acquisition   » Beginnings   » Responsible Practices   » Miscellaneous   » The Wiki Special topics   » Technochemistry   » Energetic Materials   » Biochemistry   » Radiochemistry   » Computational Models and Techniques   » Prepublication Non-chemistry   » Forum Matters   » Legal and Societal Issues