Sciencemadness Discussion Board - P2O5 and P4O10

P2O5 and P4O10

busy - 30-3-2004 at 22:23

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~~~

Esplosivo - 30-3-2004 at 22:40

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]

Pyrovus - 30-3-2004 at 23:39

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.

Esplosivo - 31-3-2004 at 00:05

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.

darkflame89 - 31-3-2004 at 01:48

But P4O10 is not only a strong dehydrating agent, it removes water too from chemicals, jus like sulphuric acid will do to sugar

lacrima97 - 8-11-2005 at 19:31

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?

BromicAcid - 8-11-2005 at 19:36

Very simply just allowing phosphorus to burn in air will generate P2O5 (Which is just another way of saying P4O10

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]

ADP - 9-11-2005 at 16:55

What type of regulations are currently placed on P2O5 in the united states? It is a very useful compound.

Magpie - 29-8-2013 at 10:42

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?

Pyro - 29-8-2013 at 14:18

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

Magpie - 29-8-2013 at 20:41

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?

Ascaridole - 11-9-2013 at 14:10

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.

AndersHoveland - 19-9-2013 at 15:10

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

plante1999 - 13-4-2014 at 07:13

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?

Texium - 13-4-2014 at 07:17

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?

Quote: Originally posted by BromicAcid

Very simply just allowing phosphorus to burn in air will generate P2O5 (Which is just another way of saying P4O10

How about that?

plante1999 - 13-4-2014 at 07:22

well, if you ever saw phosphorus burning, you would know it is not particularly practical...

Texium - 13-4-2014 at 08:26

Well, I know of no easier ways.

DoctorZET - 14-4-2014 at 09:24

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.

DoctorZET - 14-4-2014 at 11:51

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)

DoctorZET - 15-4-2014 at 03:20

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)

woelen - 15-4-2014 at 03:26

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.

Dan Vizine - 15-4-2014 at 08:26

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]

Motherload - 22-6-2014 at 12:43

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.

Magpie - 26-1-2015 at 09:27

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?

careysub - 26-1-2015 at 15:01

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