DrP
National Hazard
Posts: 625
Registered: 28-9-2005
Member Is Offline
Mood: exothermic
|
|
Urea Phosphate
I have some Urea Phosphate. All the safety data says it is compleatly harmless. When I dissolve it in water the pH drops to about 0.5!!
1) Is this phosphoric acid, Uric acid or something else>
2) How is this harmless if it produces a strong acid - wouldn't it disolve in the moisture on the skin and then burn?
Cheers!
|
|
|
chemoleo
Biochemicus Energeticus
Posts: 3005
Registered: 23-7-2003
Location: England Germany
Member Is Offline
Mood: crystalline
|
|
You have to specify a bit more:
Is it triurea phosphate, diurea phosphate or monourea phosphate?
I suspect it's the last one.
In that case, the low pH is easily explained - there are still two acid OH present, which both can form salts.
It might well burn a little, yes. But then, in principle it is similar i.e. to ammonium dihydrogen phosphate, which is also a stable yet acidic salt,
and not terribly dangerous.
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
|
|
|
DrP
National Hazard
Posts: 625
Registered: 28-9-2005
Member Is Offline
Mood: exothermic
|
|
Thanks, MSDS just says Urea Phosphate - phosphoric acid, urea salt.
Der.. I guess this answers my question - it will be phosphoric acid! ?
|
|
|
chemoleo
Biochemicus Energeticus
Posts: 3005
Registered: 23-7-2003
Location: England Germany
Member Is Offline
Mood: crystalline
|
|
Yes it is, but it is the mono-basic version. So still acidic.
Tell me, is urea phosphate your flame retardant that produces acidic conditions on the fabric? If so, you could have really written this in the same
thread, no?
Anyway - if this is the case, then I very much suspect that the acidity is in part responsible for the flame retardation, and I don't see an easy
solution to it.
Did you try to add some more urea to make it i.e. dibasic?
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
|
|
|
unionised
International Hazard
Posts: 5126
Registered: 1-11-2003
Location: UK
Member Is Offline
Mood: No Mood
|
|
Even with a monobasic acid like perchloric the salt will form an acidic solution in water.
Urea is a weak base and the corresponding ion CON2H5+ is a fairly strong acid.
|
|
|
DrP
National Hazard
Posts: 625
Registered: 28-9-2005
Member Is Offline
Mood: exothermic
|
|
Added more Urea (2, 3 and 4 times amount of phosphate) - brings pH up a fraction but not by much. Thanks.
|
|
|
Nicodem
Super Moderator
Posts: 4230
Registered: 28-12-2004
Member Is Offline
Mood: No Mood
|
|
You can't raise the pH by adding more urea. Urea in water solution can barely get protonated.
The pKa of the protonated urea is 0.18 which means it is a relatively strong acid. For comparison H3O+ has a pKa of -1.7. Hence as you see, urea
can't really be called a base in the clasic sense. It can only form salts with strong mineral acids and urea phosphate can only be one urea per
one H3PO4 and in water it is prevalently dissociated in unprotonated urea and H3PO4 and its dissociation ions (pKa1 of diluted H3PO4 is 0.9, hence
protonated urea is a stronger acid than H3PO4).
[Edited on 3-10-2005 by Nicodem]
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
|
|
|
DrP
National Hazard
Posts: 625
Registered: 28-9-2005
Member Is Offline
Mood: exothermic
|
|
I found some sodium citrate and disolved it in water - it gives a pH of around 8. This seems to bring the pH up of the Urea Phos solution up quite a
bit without leaving any salty deposits. Hopefully the mixture will still do the same job it was supposed to in the first place (ongoing tests).
I was expecting the Na Citrate to be an acidic solution because of the citrate, but I guess the Na gives NaOH??
|
|
|
neutrino
International Hazard
Posts: 1583
Registered: 20-8-2004
Location: USA
Member Is Offline
Mood: oscillating
|
|
Actually, the citrate ion is responsible for the pH.
HOH + Citrate<sup>-</sup> <--> Citric acid + OH<sup>-</sup>
This equilibrium is shifted a little to the right because citric acid is a weak acid (and thus a stable molecule).
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
