smithdotyu
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Is P2O5 dangerous
Hi all;
I have buy 500g P2O5 to make H3PO4, I think the P2O5 will react with hot water to make H3PO4。
my country china is wet this day，so I think the P2O5 will react with H2O in the air，and before I do this experiment，I prepare a glass 、a
gloves。。。and what i will need？
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Bert
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Thread Moved
4-3-2015 at 05:24 |
Bert
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Yes, it can be dangerous. The reaction will get very hot, so hot that some of the water will probably boil off. Be prepared for acid to spatter out of
the reaction vessel!
I would NOT use hot water, adding more heat for this reaction isn't needed.
If the dry P2O5 touches organic material, it may dehydrate it and get so hot that it starts a fire. Be careful and wear protective clothes/eye
protection/gloves for both chemical and thermal burns, work on an acid and heat resistant surface.
[Edited on 4-3-2015 by Bert]
Rapopart’s Rules for critical commentary:
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Metacelsus
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Why are you making phosphoric acid from your P2O5? At least where I live, phosphoric acid is much easier to get.
Anyway, make sure you add the P2O5 to the water, and not the other way around. Bert is right; use cold water.
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smithdotyu
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Quote: Originally posted by Bert  | Yes, it can be dangerous. The reaction will get very hot, so hot that some of the water will probably boil off. Be prepared for acid to spatter out of
the reaction vessel!
I would NOT use hot water, adding more heat for this reaction isn't needed.
If the dry P2O5 touches organic material, it may dehydrate it and get so hot that it starts a fire. Be careful and wear protective clothes/eye
protection/gloves for both chemical and thermal burns, work on an acid and heat resistant surface.
[Edited on 4-3-2015 by Bert] |
Thank you for your advice, this is very useful for me, in our country schoolbook said P2O5 react with cold water and make HPO3，so I use Hot
water。。。this react looks like more violent than CaO with water
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smithdotyu
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| Quote: Originally posted by Cheddite Cheese | Why are you making phosphoric acid from your P2O5? At least where I live, phosphoric acid is much easier to get.
Anyway, make sure you add the P2O5 to the water, and not the other way around. Bert is right; use cold water.
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Because I only can use experiment to buy chemical reagents，www.1688.com,you know,likes ebay in your country,think the H3PO4 is liquid and more hard
to transport
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smithdotyu
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| Quote: Originally posted by smithdotyu | | Quote: Originally posted by Cheddite Cheese | Why are you making phosphoric acid from your P2O5? At least where I live, phosphoric acid is much easier to get.
Anyway, make sure you add the P2O5 to the water, and not the other way around. Bert is right; use cold water.
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Because I only can use experiment to buy chemical reagents，www.1688.com,you know,likes ebay in your country,think the H3PO4 is liquid and more hard
to transport |
sorry for my poor English ，It is express not experiment
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Bert
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In USA, P2O5 is hard for an amateur to buy, but phosphoric acid is fairly easy to get. So USA amateurs think it strange to "waste valuable P2O5 making
cheap phosphoric acid".
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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unionised
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P2O5 reacts violently with warm water.
You are mainly warm water.
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deltaH
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| Quote: Originally posted by smithdotyu | Hi all;
I have buy 500g P2O5 to make H3PO4, I think the P2O5 will react with hot water to make H3PO4。
my country china is wet this day，so I think the P2O5 will react with H2O in the air，and before I do this experiment，I prepare a glass 、a
gloves。。。and what i will need？
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Why is the reaction with humidity a bad thing if you want to prepare phosphoric acid? Sounds like a great way to hydrate it safely. If it was me, I'd
weigh out a portion of P2O5 and its container, mark it clearly as corrosive and dangerous and keep it out of reach of people and animals, then leave
it open to hydrate from air until it forms a viscous goop, then weigh again and add enough water to ultimately form a 85% solution of phosphoric acid,
then stir and boil to complete the hydration of the polyphosphoric acids, finally, recheck mass and make-up for lost water. Seems like a great
exercise in water balancing 
[Edited on 4-3-2015 by deltaH]
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smithdotyu
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| Quote: Originally posted by deltaH | | Quote: Originally posted by smithdotyu | Hi all;
I have buy 500g P2O5 to make H3PO4, I think the P2O5 will react with hot water to make H3PO4。
my country china is wet this day，so I think the P2O5 will react with H2O in the air，and before I do this experiment，I prepare a glass 、a
gloves。。。and what i will need？
|
Why is the reaction with humidity a bad thing if you want to prepare phosphoric acid? Sounds like a great way to hydrate it safely. If it was me, I'd
weigh out a portion of P2O5 and its container, mark it clearly as corrosive and dangerous and keep it out of reach of people and animals, then leave
it open to hydrate from air until it forms a viscous goop, then weigh again and add enough water to ultimately form a 85% solution of phosphoric acid,
then stir and boil to complete the hydration of the polyphosphoric acids, finally, recheck mass and make-up for lost water. Seems like a great
exercise in water balancing
[Edited on 4-3-2015 by deltaH] |
It may come into being HPO3 not H3PO4，the HPO3 is poisonous
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smithdotyu
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| Quote: Originally posted by Bert | | In USA, P2O5 is hard for an amateur to buy, but phosphoric acid is fairly easy to get. So USA amateurs think it strange to "waste valuable P2O5 making
cheap phosphoric acid". |
I finished this experiment，I post it in our chinese website，here is，http://bbs.kechuang.org/read/70369,i don‘t record the monment when P2O5
react with water because this experiment must be careful
[Edited on 5-3-2015 by smithdotyu]
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deltaH
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Metaphosphoric acid is not poisonous, but it is corrosive being the product of a partial hydration (see attached MSDS).
Attachment: metaphosphoric acid MSDS.pdf (37kB)
This file has been downloaded 1621 times
It is also hygroscopic so it would hydrate further if left open to air. Eventually, mixing with excess water and boiling will finish it off.
[Edited on 5-3-2015 by deltaH]
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smithdotyu
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| Quote: Originally posted by deltaH |
Metaphosphoric acid is not poisonous, but it is corrosive being the product of a partial hydration (see attached MSDS).
It is also hygroscopic so it would hydrate further if left open to air. Eventually, mixing with excess water and boiling will finish it off.
[Edited on 5-3-2015 by deltaH] |
thank you, It's look's like chinese wiki about HPO3 is wrong
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deltaH
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Well, I suppose it depends how you look at it, if you eat it, it probably will kill you 
But that's because it's gonna burn the #$%^ out of you. It's only halfway in hydration between P2O5 and H3PO4 so probably a strong desiccant.
Anyhow, your final boiling step handles any outstanding hydration that is still needed.
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maleic
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It seems you already know how dangerous it is. Carefully to use it.
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chornedsnorkack
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Is the reaction of P2O5 with ice exothermic? And is it spontaneous?
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vmelkon
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HPO3? Metaphosphoric acid is (HPO3)x. I guess it is a polymeric coumpound. Free HPO3, the equivalent of HNO3 doesn't exist.
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