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Topic: What exactly is this? (Calcium phosphate)  (Read 639 times)

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Offline global

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What exactly is this? (Calcium phosphate)
« on: June 12, 2019, 08:04:21 PM »
I know that 3Ca(Po3) 2  is some form of calcium phosphate, but I could not find this exact compound.  Can someone help me identify it?

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Re: What exactly is this? (Calcium phosphate)
« Reply #1 on: June 12, 2019, 08:16:25 PM »
Such compound does not exist but CaHPO3 or Ca3(PO4)2 exist.
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Re: What exactly is this? (Calcium phosphate)
« Reply #2 on: June 13, 2019, 12:07:26 PM »
I should have added, this compound description is from the 1950's.  Is it possible that the way to describe chemical formulas have changed since then?  I doubt it, but I'm not a chemist.
Also, can you tell me what Ca3(PO4)2 is?

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Re: What exactly is this? (Calcium phosphate)
« Reply #3 on: June 13, 2019, 01:34:15 PM »
Maybe for a chemical formula from 1850, your assumption would be true. With the correct formula in the search engine you will find hundreds of pages about this compound.
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Re: What exactly is this? (Calcium phosphate)
« Reply #4 on: June 13, 2019, 08:55:18 PM »
It just comes up as calcium phosphate, or tricalcium phosphate.

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Re: What exactly is this? (Calcium phosphate)
« Reply #5 on: June 14, 2019, 03:01:26 AM »
IUPAC name is tricalcium bis(phosphate) but both your names are often used as synonyms.
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Offline David Tan

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Re: What exactly is this? (Calcium phosphate)
« Reply #6 on: June 14, 2019, 04:41:45 PM »
Ca(Po3)2 does not exist because the oxidation state of Ca in this case is +6. Calcium is a Group II element and typically loses only 2 valence electrons and carries a +2 charge. The 3rd-6th electrons are removed from an inner quantum shell and is very energetically demanding.
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Re: What exactly is this? (Calcium phosphate)
« Reply #7 on: June 15, 2019, 12:40:20 AM »
Ca(Po3)2 does not exist because the oxidation state of Ca in this case is +6.
How did you find this value?
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Re: What exactly is this? (Calcium phosphate)
« Reply #8 on: June 15, 2019, 03:25:08 AM »
For the formula as written technically he is right.

Not that it helps much, and in the context most of the information posted - although correct - is just showing off.
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Re: What exactly is this? (Calcium phosphate)
« Reply #9 on: June 15, 2019, 11:55:54 AM »
For the formula as written technically he is right.

Not that it helps much, and in the context most of the information posted - although correct - is just showing off.

This was a reply to the first post of this thread in an attempt to explain why Ca(PO3)2 is unlikely to exist. Phosphite ion has an overall charge of -3. Since we have 2 phosphite ions, the oxidation state of Ca would be +6 in this case. Respect is reciprocal. 
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Offline AWK

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Re: What exactly is this? (Calcium phosphate)
« Reply #10 on: June 15, 2019, 02:34:59 PM »
Ca(PO3)2 is the empirical formula of calcium metaphosphate. It is a polymer (Ca(PO3)2)n - n from 2 up. with n=2 show cyclic form of cyclotetraphosphate.
Oxidation number for P =+5

Added:
Phosphite ion has an overall charge of -2 and structure HPO32-
« Last Edit: June 15, 2019, 02:54:40 PM by AWK »
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Re: What exactly is this? (Calcium phosphate)
« Reply #11 on: June 15, 2019, 04:04:33 PM »
Thanks for all the responses.  So 3Ca(Po3) 2  does not exist, how about Ca3(PO3)2 ?

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Re: What exactly is this? (Calcium phosphate)
« Reply #12 on: June 15, 2019, 04:21:50 PM »
Impossible formula
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Re: What exactly is this? (Calcium phosphate)
« Reply #13 on: June 15, 2019, 10:11:13 PM »
Ca(PO3)2 is the empirical formula of calcium metaphosphate. It is a polymer (Ca(PO3)2)n - n from 2 up. with n=2 show cyclic form of cyclotetraphosphate.
Oxidation number for P =+5

Added:
Phosphite ion has an overall charge of -2 and structure HPO32-

Phosphite ion is a general term used to represent the conjugate bases of H3PO3. You are absolutely correct to state that the usual representation of phosphite ion carries a -2 charge. H3PO3 has 1 P=O, 2 P-OH and 1 P-H. However if we were to draw H3PO3 as 3 P-OH with P bearing a lone pair, then it carries a -3 charge. The latter structure adopts a trigonal pyramidal shape and is less stable than the former as the former has a strong P=O which ensures that delta G is a more negative value.
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Re: What exactly is this? (Calcium phosphate)
« Reply #14 on: June 16, 2019, 12:11:45 AM »
This tautomeric form (HO)3P  is found only in organic acid derivatives (RO)3P and is fully covalent.
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