woelen
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Phosphine from ferro phosphorus?
I have some so-called "ferro phosphorus" with appr. 25% phosphorus content by weight. I could obtain this for almost free and took some of this. It
has approximate formula Fe5P3.
I added some of this to 10% HCl, but nothing seems to happen. Even with careful heating, nothing seems to happen, only a faint green color appears in
the solution (it was colorless, the HCl used is lab-grade, colorless).
Can this {Fe,P} be used for interesting phosphorus chemistry experiments, or is this phosphorus totally locked up in this chemical?
I have a similar question about Nickel-boron, {Ni,B}. According to the person who gave this to me, this chemical has approximate formula Ni3B.
Both chemicals look somewhat metallic, but not nearly as shiny as the true metals.
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12AX7
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According to my phase diagram of the system, Fe5P3 should melt around 1550 K, consisting of a near-eutectic mixture of Fe2P and FeP phases. I would
expect it to be brittle and specular (as most intermetallics are: ferrosilicon, magnalium, Al2Cu, etc.). Given the high melting point, it's probably
relatively hard.
Heh. Suprisingly, this plot shows molten phosphorous has some solubility for the FeP phase (the most P-rich compound formed).
I would expect the iron at least to be attacked by acid, thereby releasing the phosphorous as well. I'm amazed it doesn't seem to do anything. Maybe
it's a more refractory substance than expected.
Concerning Ni and B, there are four intermetallics, NiB, Ni4B3 (hmm, interesting- inverse spinel I wonder?), Ni2B and Ni3B. All of them melt lower
than the parent elements (between 1275 and 1390 K). Although the boron may react, the nickel may be more troublesome. Maybe this one with some H2O2
in the acid?
Tim
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BromicAcid
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The nickel boride might be one of those inert almost refractory borides such as titanium boride, I can only really find information on
NiB<sub>2</sub> and that's really not all that telling.
As for your ferro phosphorus, what was its intended purpose? Just out of curiosity I worked it out to make sure you wern't talking about ferrous or
ferric phosphate (17 and 20% phosphorus respectively) since I have seen fertilizers with those kind of deceptive names. Not really sure why you're
not getting any reactivity then, Hawley's states this for ferrous phosphide:
| Quote: | Ferrous Phosphide (Iron Phosphide) Fe<sub>2</sub>P
Properties: Blue-gray powder D 6.56, mp 1290 C. Ferromagnetic. Insoluble in water.
Grade: 24-25% Phosphorus
Hazard: Evolves toxic and flammable products on exposure to moisture or acids.
Use: Iron and steel manufacture. |
So if this is ferrous phosphide (judging by the phosphorus content to ID this one), then I don't see why you're getting no reaction. Then again maybe
it is some other phosphorous/iron compound (although not likely from the elemental percentage) just like ferrous sulfide being usable for generating
H<sub>2</sub>S if it is prepared in the lab, however the mineral pyrite is not able to do the same.
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woelen
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Strange.. I heated my Fe5P3 (or Fe2P, which is actually quite close to Fe5P3) in 10% HCl. The only thing I see is that it acts as a nice boiling stone
 , but nothing more. Not even the faintest smell of PH3. After some time I quit
heating, the only thing I obtained was pungent smell of HCl.
The piece of material, however, after this treatment looks nice. It has a blue/grey appearance and has a metallic crystalline appearance, so the
description, given by BromicAcid, perfectly matches my observation. The material I have is covered by a very thin layer of brown material. Probably
this is plain rust, or some phosphate material of iron(III). This probably causes the light green/yellow color I obtain, when I add the lump of
material to the acid.
My purpose for this material was to make phosphine in a reasonably pure state (with the only dilutant being hydrogen). I also expected this to work
like FeS, but things turn out otherwise  .
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not_important
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Before you give up, you might try fairly hot sulfuric acid, although all the data I can find indicates it takes oxidising acids to dissolve it which
would be expected to give phosphate.
Wonder if this could be used to make PCl3 or PBr3 by reaction with the halogen. The phosphorous halides are of more interest on the organic side, but
with the difficulty for many people in obtaining the halides or elemental phosphorous to make them from this could be a useful route to the halides.
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