tetracalcium phosphate

Could anyone tell me something about tetracalcium phosphate Ca4P2O9?

What is the different from this mineral to tricalcium phosphate while
its formular look like Ca3PO4 . Cao ?

Can we produce it in the condition under 1000 C ?
With best regards. Thieu Triet

> Could anyone tell me something about tetracalcium phosphate Ca4P2O9?

This is what would be commonly called calcium pyrophosphate.


Let's just say it is part of the (CaO)x.(P2O5)y family.


Theoretically you should be able to produce it by heating
CaHPO4 or Ca(H2PO4)2, but phosphates form a whole family of
polyphosphate anions so you would have a hard time getting
a defined product.

Maybe precipitation from sodium pyrophosphate would be the
easiest prep.

Paddy

wouldn't calcium pyrophosphate be Ca2P2O7 ??

a quick (gross) search on altavista returned things like
Ca4(PO4)2O, an oxyphosphate.

see, for example, [Only registered users see links. ]

"Paddy" <[Only registered users see links. ].bg> escreveu na mensagem
news:[Only registered users see links. ] m...


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> wouldn't calcium pyrophosphate be Ca2P2O7 ??

You're correct. I should have called it a polyphosphate but
that is an undefined term that covers a lot of phosphate chem.

My suggestion to precipitate the polyphosphate from solution
would probably not work either, even if one could get or
prepare Na8P2O9, because some polyphosphates are commonly used
to dissolve calcium scale and will even dissolve cement.

"Thieu Minh Triet" <[Only registered users see links. ]> wrote in message
news:71e1c728.0307210435.15b05277@posting.google.c om...

No difference, if you write tricalcium phosphate as Ca3(PO4)2. Then, you're
one CaO away from Ca4P2O9.

Eric Lucas

Then tetracalcium phosphate is much more soluble than other calcium
phosphate minerals just because it has CaO ? Is that the main reason ?
Best regards. Thieu Triet

[ionimp]

So, is it, or is it not possible to precipitate tetracalcium phosphate? I know that production via sintering is widely used and known to those of this area, but in general, it is the dicalcium phosphates (anhydrous and dihydrous), octacalcium phosphates and hydroxyapatitites that are mainly produced via precipitation and that the tricalcium phosphates (alpha and beta) and tetracalcium phosphate that is produced via sintering.

Any info regarding the process to precipitate tetracalcium phosphate would be welcomed.