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posted by  monkeyJ on 4/4/2008 8:18:32 PM  |  status: Closed  

Please help !! lifesaver!!

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General Chemistry N/A N/A N/A
Question Details:
As a result of mineral erosion and biological activity, phosphate ion is common in natural waters, where it often precipitates as insoluble salts, such as Ca3(PO4)2. Calculate Qsp when [Ca2+]init = [PO43-]init = 4.532 10-6 M in a given river.

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posted by science-girl on 4/5/2008 2:32:26 PM  |  status: Live
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[Ca2+]3[PO4]2=Qsp
 
(4.532 x 10-6)3(4.532 x 10-6)2  = 1.91 x 10-27
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posted by thatsme on 4/5/2008 3:06:42 PM  |  status: Live
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Response Details:
Qsp is the same as Ksp calculation however you need to use initial concentrations

Ca3(PO4)2---> 3Ca+2  + 2PO4-3
use stoich coefficients as powers, don't forget that whatever the [Ca] is, it needs to be multiplied by 3 and the [PO4] needs to be multiplied by 2, before being substituted into the Qsp calculation.
use this to get Qsp
Qsp= [Ca+3]3[PO4-3]2
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