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posted by  Chuperstar on 6/3/2008 9:52:47 PM  |  status: Live  

Limiting Reactant - Urgent Help! Will Rate all who contribute.. Respect speaks for itself:)

Course Textbook Chapter Problem
General Chemistry N/A N/A N/A
Question Details:
Chemical Reaction:

3Ba2+(aq) + 2PO43-(aq) ---> Ba3(PO4)2 (s)

Mass of salt mixture: 0.998 g
Mass of Ba3(PO4)2 precipitate: 0.2949 g

Moles of Ba3(PO4)2:        ??????????????????????? moles
 
Please show Calculations.

∴ The limiting reactant in the salt mixture is ____________ .

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posted by gopackgo on 6/3/2008 10:24:33 PM  |  status: Live
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Chuperstar's comment:
"Thnx for the 2nd part but i kinda need to noe the moles of ba3po4_2 too"
Response Details:
PO4
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posted by CramminSince88 on 6/3/2008 11:11:37 PM  |  status: Live
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Chuperstar's comment:
"rated helpful....can anyone show how to derive the number of moles and why po4 is the limiting reactant"
Response Details:
phosphate
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posted by Zedekiah on 6/4/2008 12:59:59 PM  |  status: Live
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Chuperstar's comment:
"rateddd....thnx"
Response Details:
I believe we need more information to solve this problem.  (About the nature of the salt mixture).  It could contain any number of things that prevent us from determining which is the limiting reactant.

3Ba2+(aq) + 2PO43-(aq) ---> Ba3(PO4)2 (s)

The first thing you'll want to do is determine the mole quantity of each from the grams.

Grams may be converted to moles based on molar mass.



Where μ is the molar mass in grams per mole.

The molar mass of barium phosphate is 601.924 g / mol

If 0.2949 grams of barium phosphate precipitates, the mole quantity that precipitated was :



= 0.0004899 moles of Barium phosphate.

Working backwards, we can now find the moles of barium and phosphate.

There are three times as many moles of barium as there are of barium phosphate.
0.0004899 * 3 = 0.0014700 moles
Barium has a molar mass of 137.327 g / mol.
There are 0.2019 grams of barium in the salt.

There are two times as many moles of phosphate of barium phosphate.
0.0004899 * 2 = 0.0009798 moles
Phosphate has a molar mass of 94.9714 g / mol.
There are 0.09305 grams of phosphate in the mixture.


This is where we get stuck.  There is no way of knowing with this information which the limiting reactant is.  We would have to know something more about the composition of the salt mixture.

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posted by vballdude on 6/5/2008 1:05:49 AM  |  status: Live
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Response Details:
PO4 also known as phoshate
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