busy
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P2O5 and P4O10
Is both of P2O5 and P4O10 are dehydation agent??
Also, does they have any other chemical proporties? (e.g. react with something?)
if yes. what is that?
any recommended website for that?
I hope there are someone can tell me
THanks~~~
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Esplosivo
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A quick google search will give up many information. Just to help you out here is the MSDS of phosphorus pentoxide:
http://ptcl.chem.ox.ac.uk/MSDS/PH/phosphorus_pentoxide.html
and for diphosphorus pentoxide:
http://avogadro.chem.iastate.edu/MSDS/P2O5.htm
If you check out the MSDSs you will find out that they are pretty reactive. And they do react with water, but they are not termed as dehydrating
agents, but as hygroscopic or deliquescent, ie it absorbs water from the atmosphere to become saturated or dissolve in the water absorbed
respecitvely.
Edit: BTW, next time post this is the beginnings section, were I think it is more suited.
[Edited on 31-3-2004 by Esplosivo]
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Pyrovus
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Well, for starters P2O5 and P4O10 are the same thing - the actual molecule is P4O10, but it is often written as P2O5. It is a strong dehydrating agent
because it is the acid anhydride of phosphoric acid, so it reacts with water to form the acid. As phosphoric acid shows little tendency to decompose
back into water and phosphorous pentoxide, the equilbrium
P2O5 + 3H2O <-> 2H3PO4 lies exclusively to the right. All acidic oxides are dehydrating agents to some degree; their strength is determined by
how far to the right their equilibrium lies. For instance, carbon dioxide could -technically- be considered a dehydrating agent (albeit hideously
weak), as it reacts with water as follows: CO2 + H2O <-> H2CO3. But the equilibrium lies mostly to the left, so it's capacity to get rid of
water by reacting with it is minescule.
Never accept that which can be changed.
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Esplosivo
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busy, is this for some project or do you require any dehydrating agent. In that case, phosphoric acid is a better dehydrating agent than the oxides.
It is used in industrial prep. of alkenes from alkanes for example.
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darkflame89
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But P4O10 is not only a strong dehydrating agent, it removes water too from chemicals, jus like sulphuric acid will do to sugar
Ignis ubique latet, naturam amplectitur omnem.
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lacrima97
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Does anyone have a synthesis for P4O10? Would the extreme heating of elemental phosphorus in a 21% oxygen atmosphere possibly bring about the
formation of this substance?
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BromicAcid
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Very simply just allowing phosphorus to burn in air will generate P<sub>2</sub>O<sub>5</sub> (Which is just another way of
saying P<sub>4</sub>O<sub>10</sub> White phosphorus will
actually catch on fire on its own and burn, but if there is not enough air a lower phosphorus oxide will form. Small amounts could be made with the
aid of a bell jar, be warned the toxicity of white phosphorus, but if you're using red you are considerably safer.
[Edited on 11/9/2005 by BromicAcid]
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ADP
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What type of regulations are currently placed on P2O5 in the united states? It is a very useful compound.
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Magpie
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Quote: Originally posted by ADP  | | What type of regulations are currently placed on P2O5 in the united states? It is a very useful compound. |
This is a very old thread but as far as I know ADP's question is still relevant for those residing in the US.
I cannot find a source for P2O5. I don't know if it is available in Canada? Can anyone tell me a source for a US resident?
The single most important condition for a successful synthesis is good mixing - Nicodem
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Pyro
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I believe that P2O5 can only exist at high temperatures, at low temperatures it is P4O10.
here is where I bought mine:
http://www.ebay.com/itm/PHOSPHORUS-PENTOXIDE-P2O5-250g-PURTY...
they ship worldwide
it has a few impurities but is good for just about anything you need it for.
as for making it, seems wasteful and a little dangerous. but burn P or P4 and condense the vapour
http://www.youtube.com/watch?v=U6_-EUcswSc at the end you can see a dusting of P4O10 on the walls of the flask
all above information is intellectual property of Pyro.  |
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Magpie
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Thanks Pyro for that source. The price looks reasonable.
From what I can tell P4O10 is not listed or watched by US authorities. However, coming from Poland means that it would be subject to possible US
Customs inspection. I have never bought any chemicals from overseas so don't know if this would bring me any trouble. What is the experience of
others?
The single most important condition for a successful synthesis is good mixing - Nicodem
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Ascaridole
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Magpie, You are correct P4O10 is not watched by the DEA however shipping is a pain. The local supply company I use had to special order it and had to
have it shipped by its self as a corrosive solid not compatible with other acids. 
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AndersHoveland
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If you were wondering, P2O5 and P4O10 are basically the same compound but different forms. The gas phase is usually P4O10, and can be directly
condensed into a solid, with the definite molecular formula P4O10. This solid is analogous to "flowers of sulfur". In contrast, P2O5 implies that the
solid has definite chemical composition ratio, but is an intermolecular compound. The best analogy I can think of is comparing trioxane to
polyoxymethylene plastic (formaldehyde has several different chemical forms). P2O5 is just the empirical formula. The only reason it is not written
with only phosphorous is because the 5 oxygens are not divisible by 2.
| Quote: | Phosphorous pentoxide exists in at least four polymorphic forms as well as a glass. the common variety of laboratory and commerce... consists of large
cage molecules... with only weak van der Waals-type forces between cages. There are also two orthorhomic crystalline forms which contain highly
polymerised arrangements (P2O5)n. ... The vapor from these forms is stable up to at least 1400 C, and at high temperatures the existence of dimeric
species is possible.
The three forms... have interesting differences in properties which can be related to their crystal structures. The highly polymerized forms have
higher melting points than the [P4O10] form. All three forms can be vaporized to produce the same cage molecules which exist in the [P4O10] form, but
there are differences in the liquids produced by melting.
The [P4O10] form first melts at 420 C to produce the metastable liquid with a high vapor pressure and consisting of discrete P4O10 units. This liquid
then rapidly polymerizes to form a glass... [which melts] at 562 C to give viscous liquid... Both [polymerized] forms are considerably less
deliquescent than the [P4O10] form.
Phosphorus: Chemistry, Biochemistry and Technology, Sixth Edition,D. E. C. Corbridge
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plante1999
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I have some red phosphorus, and I would like to get some phosphorus pentoxide, does anyone have a preparation, or a source for the said chemical?
I never asked for this.
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Texium
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| Quote: Originally posted by plante1999 | I have some red phosphorus, and I would like to get some phosphorus pentoxide, does anyone have a preparation, or a source for the said chemical?
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| Quote: Originally posted by BromicAcid | Very simply just allowing phosphorus to burn in air will generate P<sub>2</sub>O<sub>5</sub> (Which is just another way of
saying P<sub>4</sub>O<sub>10</sub> White phosphorus will
actually catch on fire on its own and burn, but if there is not enough air a lower phosphorus oxide will form. Small amounts could be made with the
aid of a bell jar, be warned the toxicity of white phosphorus, but if you're using red you are considerably safer.
[Edited on 11/9/2005 by BromicAcid] |
How about that?
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plante1999
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well, if you ever saw phosphorus burning, you would know it is not particularly practical...
I never asked for this.
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Texium
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Well, I know of no easier ways.
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DoctorZET
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well...there might be other ways to oxidate phosphorus...
here are 2 links for all who want to "cook" white phosphorus at home:
~LINK: https://www.sciencemadness.org/whisper/files.php?pid=317264&... ~
~LINK: https://www.sciencemadness.org/whisper/viewthread.php?tid=65... ~
Ok, now let's see how can we oxidate the white phosphorus to P2O5/P4O10 (Both formulas are corect):
First, come into my mind, a simple reaction: P4 + 5O2 -(heat from a safety match)-> P4O10 + (a_lot_of_light) + (some_heat)
That's a beautiful epic reaction, but not a very practical one...
So, we need an other something ... remember the reaction between Charcoal and Nitric acid? :
C + 4 HNO3 --> CO2 + 4 NO2 + 2 H2O ... yes ... this boring useless reaction
Well, it's not so "useless"... because it makes us think about an other tipe of oxidation reaction: instead of burning phosphorus in O2/air, we can
oxidate it in solid/liquid form:
P + 5HNO3 ---> H3PO4 + 5NO2 + H2O
But we need to think about an oxidant agent who do not contain H-O bonds, because we need P2O5, not H3PO4 !
KCr2O7 , KMnO4, Ca(OCl)2, ClO2, N2O4, BaO2, PbO2, AgO, etc. are just a few oxidizing agents wich has no H-O bonds
so, we might be able to carefully oxidate the P4 to P2O5, without burning the phosphorus.
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DoctorZET
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I think about next 2 reactions:
P4 (CCl4 solution ) + 5 N2O4 --(? ...heat/UV/pressure)--> 10 NO^ + P4O10 (s)
2P4 (CCl4 solution) + 10 ClO2 --(intense blue/UV light)--> 5 Cl2^ + 2 P4O10 (s)
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DoctorZET
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I just tried first reaction and the P4 burns in N2O4 ... is like burning P4 in NO2 atmosphere ... not very practical, but it works better with smaller
pieces of phosphorus, because the P4O10 remain in the liquid dinitrogen pentoxide as suspension and the dinitrogen pentoxide remain liquid 
P4 + 5 N2O4 --(activation energy = a hot iron wire)--> 10 NO^ + P4O10 (s)
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woelen
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I think that burning phosphorus is the only practical option. This is how it is done industrially. The challenge is more an engineering one than a
chemical one. You need to construct some device which traps the white very fluffy smoke, while allowing spent air to pass through.
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Dan Vizine
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Wow, I just looked and you can even get P2O5 on eBay in the US. Prices aren't criminal. Cool.
Funny, I've long wanted it but just assumed that it wouldn't be there. I don't think it was there years ago. But now...dehydration nirvana has
reentered my life...
Oh eBay, just what chemical won't you sell (even if it is often unwittingly)!?
(I was surprised to see absolute ethanol too. I don't think anybody has offered sulfur trioxide or oleum yet. Not sure about fuming nitric. Sorry for
rambling....)
[Edited on 15-4-2014 by Dan Vizine]
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Motherload
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I have been searching for the decomposition temperature of Cupric Phosphate.
Can't find squat. Although I did find some loose references suggesting it decomposes to CuO and P2O5.
Since I have Cu2SO4 and Tri Sodium Phosphate readily available ..... I want to see how efficient it is .
But I can't find the decomp temp for Cupric Phosphate.
"Chance favours the prepared mind"
"Fuck It !! We'll do it live !!"
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Magpie
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P2O5 is a chemical that home chemists occasionally need. However, I do not know of a source in the US. So, this post is to ask tomholm at Elemental
Scientific if he could sell it. If so, under what conditions of hazmat fee, quantity, and price?
The single most important condition for a successful synthesis is good mixing - Nicodem
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careysub
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| Quote: Originally posted by Magpie | | P2O5 is a chemical that home chemists occasionally need. However, I do not know of a source in the US. So, this post is to ask tomholm at Elemental
Scientific if he could sell it. If so, under what conditions of hazmat fee, quantity, and price? |
Firefox-FX carries phosphorus pentoxide, and at a reasonable price ($21/lb). It does not require an exhorbitant hazmat fee either.
http://www.firefox-fx.com/ChemN-P.htm
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