Jor
National Hazard
Posts: 950
Registered: 21-11-2007
Member Is Offline
Mood: No Mood
|
|
today have done an experiment with White P
Today I wanted to burn some White P for my webpage. I have 3 gram, a gift (well paid a little money) from woelen.
Unfortunately I by accident deleted the movie, so Iwill have to do it again.
This is how everything went.
I added a small piece, I think about 100mg to a 250mL flask, wich had a layer of NaCl at the bottom (heat absorption). Next I touched it with a heated
glass rod, and it catched fire. I pulled out the glass rod, and put a watch glass on the flask. The glass rod was burning (some white P). At this
point I smelled garlic. I didn't expect the white phosphorus smell to come from buring white P  . I stepped out of the lab and ventilated. Next I heated the glass rod with a flame for a minute or so to destroy all
phosphorus. I then prepared a solution of chlorine, so 1mL concetrated HCl, 3mL of water and 2mL of bleach and added this to the flask to destroy
remains of phosphorus. After 1 minute there was still some ORANGE (the 'white' P i used was dark yellow/orange) remains, wich were not attacked by the
still yellow liquid (chlorine). Addition off fresh chlorine-solution did not help.
What is this material? White P should be attacked instantly by Cl2 right?
Is White P as toxic by inhalation as it is by ingestion (ingestion LD50 about 50mg)? Have I breathed dangerous concentrations by smelling it?
I find it weird that P4 molecules can survive in air as a gas, they should be attacked by O2 instantly .....
|
|
|
panziandi
Hazard to Others
Posts: 490
Registered: 3-10-2006
Location: UK
Member Is Offline
Mood: Bored
|
|
White P is very toxic! My white P is pale yellow waxey rods (reagent grade) stored under water. When you open the jar it is usual to smell a faint
smell of "garlic" or similar peculiar smell. I just try to avoid inhaling it. I would be more worried about having a piece touch my skin and ignite
than I would be having a whiff of garlic. The orange colour in your sample in undoubtedly due to red phosphorus contamination. Red phosphorus is much
less reactive than white allotrope and I would not be surprised if it reacted slowely if at all with chlorine water. White phosphorous is so unstable
that your experiment would have left no unreacted (or no significant / dangerous quantity) in the flask. P4 is oxidised in air by O2 this is the
principal behind the "green flame" or "cold falme" "ghost flame" experiments.
[Edited on 7-10-2008 by panziandi]
|
|
|
woelen
Super Administrator
Posts: 7977
Registered: 20-8-2005
Location: Netherlands
Member Is Offline
Mood: interested
|
|
White P, when heated, partially is converted to red P. The orange material probably contains quite some red P, which does not react as quickly as
white P. But if you keep the solution of chlorine in contact with the orange material, then it finally will dissolve completely.
The 'white' P you have indeed is yellow with an orange tinge. This impurity also is red P. This impurity is quite common when white P is made by
heating red P (this is how I made the white P) and is filtered with glass wool. Making really white phosphorus can be done by dissolving the yellow
phosphorus in CS2 and filtering the liquid with very fine filtering paper. The liquid then must be evaporated (in the absence of air!!) and what
remains is white P. This white P, however, quickly becomes yellow/orange again, when light hits the solid.
I think that the specific smell of white P indeed is white P. At low concentration, the reaction between white P and oxygen is so slow that it can
survive for some time in air. This also makes it possible to see the glow of white P in air. You do not need white P for that experiment, take a small
spatula of red P and heat the loosely stoppered (glasswool or cotton wool) test tube with the red P, until some of it is converted to white P. Let the
test tube cool down and then remove the glass wool or cotton wool while being in a dark place. You can see a yellow/green ghostly glow of the fumes in
the test tube.
@Panziandi: Even if you burn very pure really white P, then some orange material remains. So, a small amount of white P really is converted to red P
under such conditions.
[Edited on 7-10-08 by woelen]
|
|
|
Picric-A
National Hazard
Posts: 796
Registered: 1-5-2008
Location: England
Member Is Offline
Mood: Fuming
|
|
By a simple smell i doubt it is amazingly dangerous but still not good for you. To be on the safe side if you feel any of the syntoms, get help,
phossy jaw is nasty!
I dont think white P is attacked readily by chlorine sol. try dissolving it in CS2 then evaporating safely to burn off remainding white P.
They are attacked by O2 molecules... where did you find out they arnt attacked by O2?
|
|
|
woelen
Super Administrator
Posts: 7977
Registered: 20-8-2005
Location: Netherlands
Member Is Offline
Mood: interested
|
|
Oh yes, white P is attacked by chlorine solution very easily. If the solution is somewhat more concentrated, then even quite some heat is produced.
Even red P is dissolved by a solution of chlorine, but that takes more time.
|
|
|
smuv
National Hazard
Posts: 842
Registered: 2-5-2007
Member Is Offline
Mood: Jingoistic
|
|
This garlic smell is probably PH3/P2H4, a product of the reaction of phosphorous with water; definitely try to minimize exposure to this.
"Titanium tetrachloride…You sly temptress." --Walter Bishop
|
|
|
panziandi
Hazard to Others
Posts: 490
Registered: 3-10-2006
Location: UK
Member Is Offline
Mood: Bored
|
|
Indeed I believed the smell to be PH3 by hydrolysis of the P4 by H2O. My WP has been stored in the dark under original water for perhaps 20-odd years
and is still pale yellow.
@ Woelen: I know that WP is unstable and readily forms RP, I was saying that the orange colour can be attributed to RP impurity. I was saying that
when WP combusts in this manner of experiment that once teh reaction is over the danger of WP is negligable since there is almost certainly none left,
either combusted or indeed converted to RP (which too could easily burn given the heat produced from the WP burning), so Jor was decontaminating the
flask etc which I think is a little over kill to worry about since the WP almost certainly reacted to completeness.
|
|
|
Jor
National Hazard
Posts: 950
Registered: 21-11-2007
Member Is Offline
Mood: No Mood
|
|
Panzaiadi, where did you buy your white phoshorus. Seems that it is unavailable. Sigma-aldrich, Acros and Merck don't list it in their catalogue.
Smuv, how can phosphine be formed in when burning the phosphorus? Where do the hydrogens and electrons come from?
And does phosphorus react with water under formation of phosphine? Why is it stored under water then? The only possible reaction I can make up is:
P4 + 6 H2O -->2 PH3 + 2 P(OH)3 (phosphorous acid)
I don't think it has all burned. I smelled some ... I closed the flask with a watchglass to keep irritaing fumes in the flask. Maybe the phosphorus
was in excess?
But I do not have to worry about inhaling ca. 2 breaths where there was a faint smell of garlic (and I even immediatly breath out as much air as I
could.)? Besides I breathed a little of chlorine, maybe antidote? 
i will handle it only next time when my fumehood is done (will take some time, dad very busy).
|
|
|
Jor
National Hazard
Posts: 950
Registered: 21-11-2007
Member Is Offline
Mood: No Mood
|
|
Ive been reading on the subject, and now I think the garlic smell was more likely phosphorus trioxide.
http://www.tpub.com/content/ArmyCRREL/CR95_23/CR95_230008.ht...
Read the upper part of the right column. When limited oxygen is present phosphorus trioxide is formed wich is responsible for the immediate garlic
odor when phosphorus is burned.
Alos if my English is correct in the last paragraph it is said that white P, when present as vapor under a certain limit concentration it reacts with
oxygen very slow? Is this correct or does my English just suck? 
http://www.ucc.ie/academic/chem/dolchem/html/comp/po3.html
I placed a watch-glass on the flask, so indeed limited oxygen.
In HOT water, this oxide hydrolyses to phosphoric acid and phosphine. I cold water it hydrolyses to phosphorous acid.
So probably most of the garlic was this oxide. Still toxic, but I think less then white P and I think also no chronic effects!
[Edited on 7-10-2008 by Jor]
|
|
|
panziandi
Hazard to Others
Posts: 490
Registered: 3-10-2006
Location: UK
Member Is Offline
Mood: Bored
|
|
Mine is very old about 20-odd years old! I think it's BDH. I got it off a friend who purchased it legit years ago. It is no longer manufactured for
retail as fair as I know. If you require it in a lab you would usually prepare it yourself I expect (especially as the only research uses for it
require highly purified material anyway or "nicer" alternatives) I believe it is still manufactured by Chinese companies so potential there, but much
easier to source the red allotrope and distil that if you require it Jor.
I believe it can react very slowly and self-limiting with water to yield a small quantity of phosphine, the water in the jar is acidic (but that could
equally come from phosphoric acid from any residual P2O5), but it does react with alkali to yield PH3 so maybe with water it yields PH3 and H+ which
then prevents further reaction.
It's stored under water because it either reacts with other compounds or dissolves in them!
I doubt 100mg was an excess! The faint smell is likely a small quantity of vapour that formed as the WP combusted. When I do this reaction I do it on
a tile usually that way all of the P2O5 blows away from me and any WP vapours are carried away and I have no problems (not as impressive as in a jar
of oxygen enriched air mind!). I wouldn't be too worried about handling small quantities in the open so long as you wear gloves and cut under water
and don't touch or eat it or drink the water lol!
I personally found no use for WP other than the usual combustion tricks which seems a waste of such a beautiful chemical!
|
|
|
Jor
National Hazard
Posts: 950
Registered: 21-11-2007
Member Is Offline
Mood: No Mood
|
|
Another use is reacting it chlorine to form phosphorus trichloride. Phosphorus trichloride cannot be prepared from red P. Don't use excess chlorine,
or you might chlorinate to PCl5.
|
|
|
panziandi
Hazard to Others
Posts: 490
Registered: 3-10-2006
Location: UK
Member Is Offline
Mood: Bored
|
|
Well luckily I have plenty of the phosphorous chlorides so I don't need to waste the WP on preparing them.
I have a small sample in my element collection. I use small samples in CS2 for use as flammable ink sometimes. And sometimes I'll use it for a little
fun demo with my sibblings and mates but usually it's just a jar I like to keep locked up!
|
|
|
woelen
Super Administrator
Posts: 7977
Registered: 20-8-2005
Location: Netherlands
Member Is Offline
Mood: interested
|
|
Yes, white phosphorus is very fun for experiments, but it hardly has any synthetic uses. That's why I made two batches of 3 grams or so from red P
(one of these batches now is at Jor's place) and I only use the stuff for fun experiments, just like Panziandi does. I found that it is almost
impossible to make really white P, even with very fine filtering the material remains yellow, but for the demos that is of no concern. So, I do not
feel the need to really buy the chemical from a supplier. Till recently there was a supplier (www.chemikalien-shop.de), who sold white P in 15 gram quantities, but unfortunately this does not exist anymore and I never bothered to buy the
stuff (I was afraid of having it shipped to me through international post, I did not like that idea at all). Instead I made some myself.
|
|
|
Ozonelabs
Hazard to Others
Posts: 120
Registered: 5-4-2008
Member Is Offline
Mood: Oligomerised
|
|
Here is our video of this experiment with pictures of the colour of 'white' P.
http://www.youtube.com/watch?v=XRamWIZUKhI
Enjoy
|
|
|
chloric1
International Hazard
Posts: 1070
Registered: 8-10-2003
Location: GroupVII of the periodic table
Member Is Offline
Mood: Stoichiometrically Balanced
|
|
WP can be hydrolisized by aqueous alkali to for hypophosphite. This is usefull for electroless nickel and simular reductions.
Fellow molecular manipulator
|
|
|
panziandi
Hazard to Others
Posts: 490
Registered: 3-10-2006
Location: UK
Member Is Offline
Mood: Bored
|
|
Yes we mentioned hypophosphite in a thread about replacing the diazonium group to a hydrogen. You can usually buy hypophosphites unless you live in
the US where both are restricted but lets not get that topic up AGAIN. WP has limited synthetic uses its is moreover used for fun demos. Ozonelabs:
nice video!
|
|
|
woelen
Super Administrator
Posts: 7977
Registered: 20-8-2005
Location: Netherlands
Member Is Offline
Mood: interested
|
|
Another very nice experiment in which white P is hydrolysed is adding the solid to a concentrated solution of KOH or NaOH in a test tube with 'inert'
atmosphere (e.g. butane) and then carefully heating. Phosphine, contaminated with P2H4, is formed and as soon as this comes in contact with air, it
ignites. If you take the test tube in which the gas is produced, and you use a thin rubber tube and let bubbles of this gas mix go through water, then
at the surface, as soon as the bubbles come in contact with air, they ignite, giving rings of white smoke of P4O10.
|
|
|
Jor
National Hazard
Posts: 950
Registered: 21-11-2007
Member Is Offline
Mood: No Mood
|
|
I did the experiment again, now in my fume hood. I put a small piece of white P in the flask (I think it was about 100mg), and ignited with a hot
glass rod. It immediatly ignited.
http://sites.google.com/site/chemlabchemistry/experiments-1/...
Also have a look at my other experiments.
Please not that, although it looks like smoke escapes from the hood, none gets out at all, I smelled nothing.
|
|
|
JohnWW
International Hazard
Posts: 2849
Registered: 27-7-2004
Location: New Zealand
Member Is Offline
Mood: No Mood
|
|
You will have to be very careful about inhaling or ingesting the stuff, even amounts very much less than known lethal doses. White P causes "phossy
jaw", in which the bones of the jaw erode with resulting tooth loss. White As also has the same effect, and is, additionally, acutely toxic in larger
quantities. Workers in match factories in which white P was once used as an ingredient to make P2S3 for the match tips suffered badly from it.
In larger quantities, white P, is an acute liver toxin; - mixed into an apple jam (which glows in the dark), it has been used as a pesticide here in
New Zealand to kill the introduced Australian brushtail opossum (N.Z.'s number one pest), although this has been largely superseded by jams containing
cyanide (for instant kills where the fur or pelt is desired to be retrieved), or cereal pellets containing sodium monofluoroacetate (1080) and
containing an attractant such as cinnamon oil. The poison pastes and pellets contain a green dye to render them unattractive to non-target species,
particularly birds.
|
|
|
a_bab
Hazard to Others
Posts: 458
Registered: 15-9-2002
Member Is Offline
Mood: Angry !!!!!111111...2?!
|
|
Ok, here are my thoughts for this thread.
Even if the WP is so reactive to the oxygen, it is stated in the literature that it has that "garlic like" smell. On the other hand, if you read that
amasing book about phosphorus "the sordid story...", there are some accidents listed; the common conception is that in a phosphorus fire the fumes are
not *that* toxic, as the resulted phosphorus oxides are known to have a low toxicity and the phosphorus vapors can't exist in air. Still, people pass
out in phosphorus fumes and/or they feel dizzy.
Well, I guess that phosphorus vapors can be smelled. On opening a bottle as someone suggested, not only you feel the garlic smell, but the fact that
the vapors will quickly react with the air and create a visible white "fog" is the prove that this is the smell of WP.
On the other hand, given the fact that a lethal dose of WP should be around 0.1 grams or such for an adult, smelling the WP won't give you "instant
phossy jaw" unless you did it for several years, 8-10 hours a day (not all the people were affected and the ones affected were literally in a WP
"plume" for years; they must have felt the smell all the time). So I personally find the danger of taking a whiff rather... amusing to say the least.
It's not the substance that it's dangerous, but the level of knowledge related to it. One can feel the smell of WP and drop dead because he "knows"
that is extremly toxic (there are similar cases reported with HCN involved; people had died in way lower concentrations that the lethal dose due to
autosuggestion).
a_bab, once the proud owner of some 1 kg of red P and 100 grams of WP.
|
|
|
woelen
Super Administrator
Posts: 7977
Registered: 20-8-2005
Location: Netherlands
Member Is Offline
Mood: interested
|
|
I agree with a_bab. The warning of JohnWW is good, but things should not be exaggerated. I also have some white P (just a few grams of home made
material) and of course I have smelled the stuff, while making it and also when doing experiments at a later time. But the total number of exposures
is around 5 over a period of almost one year and the exposures were low (only smelling it for a few seconds). With such exposures you certainly will
not get "phossy jaw".
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
