Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
Author: Subject: Is diphosphorus pentoxide hygroscopic?
chornedsnorkack
National Hazard
****




Posts: 419
Registered: 16-2-2012
Member Is Offline

Mood: No Mood

[*] posted on 18-6-2021 at 13:07
Is diphosphorus pentoxide hygroscopic?


Seriously.

Compare the example of phosphorus itself.
When phosphorus vapours are rapidly condensed, P4 condenses. P4 melts at 44 Celsius and boils at 280 Celsius.

But on prolonged heating, P4 is converted into P. Red P sublimes at 430 C without melting, and under pressure melts at 590 C.

Their reactivity is quite different!

P4 reacts with air to glow in dark at room temperature and readily ignites at room temperature - red P only burns above 200 C.
P4 is dismuted by hot aqueous alkali, like
P4+3KOH+3H2O=PH3+3KPH2O2
Red P is not.
P4 readily reacts with body to form poisonous amino bisphosphonates - red P does not.

Now compare phosphorus pentoxide...
On quick cooling, hexagonal P4O10 is condensed.
It sublimes at 360 C without melting, and under pressure melts at 423 C.
And P4O10 is notoriously hygroscopic.

But on prolonged heating, P4O10 converts into P2O5, which is orthorhombic, and melts at 580 C into a viscous liquid which boils about 600 C.

Considering the vapour pressure difference between hexagonal P4O10 and orthorhombic P2O5, is their chemical reactivity also different? Is P2O5 hygroscopic?
View user's profile View All Posts By User
njl
International Hazard
*****




Posts: 583
Registered: 26-11-2019
Location: under the sycamore tree
Member Is Offline

Mood: ambivalent

[*] posted on 19-6-2021 at 06:39


Yeah



Reflux condenser?? I barely know her!
View user's profile View All Posts By User
Tsjerk
International Hazard
*****




Posts: 2455
Registered: 20-4-2005
Location: Netherlands
Member Is Offline

Mood: Mood

[*] posted on 19-6-2021 at 11:48


Hygroscopicity is a physical property which happens via absorption or adsorption, so P2O5 (P4O10) can't be hygroscopic because it reacts with water.

https://en.m.wikipedia.org/wiki/Hygroscopy

Also P2O5 is not a molecule.
View user's profile View All Posts By User
karlosĀ³
International Hazard
*****




Posts: 1354
Registered: 10-1-2011
Location: yes!
Member Is Online

Mood: aminoketonologisch 8)

[*] posted on 19-6-2021 at 11:59


P4O10, sorry :D
View user's profile View All Posts By User
chornedsnorkack
National Hazard
****




Posts: 419
Registered: 16-2-2012
Member Is Offline

Mood: No Mood

[*] posted on 19-6-2021 at 12:15


Quote: Originally posted by Tsjerk  

Also P2O5 is not a molecule.


Indeed it is not.
The hexagonal form consists of distinct molecules - of P4O10.
However, the orthorhombic form is infinite covalent polymer that does not consist of molecules. Therefore it is P2O5, not P4O10.
View user's profile View All Posts By User
Tsjerk
International Hazard
*****




Posts: 2455
Registered: 20-4-2005
Location: Netherlands
Member Is Offline

Mood: Mood

[*] posted on 19-6-2021 at 12:47


No, it would be P2O5(n).
View user's profile View All Posts By User

  Go To Top