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moles qn (1 Viewer)

bos1234

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Oct 9, 2006
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HSC
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A total of 10.0g of sodium chloride is weighed out and dissolved in sufficient water to make 200ml of soln. A. 50ml of soln. A is removed and mixed with 250ml of water to make soln. B. Calculate molarity of

soln. A

soln. B

I got the answer to soln. A 0.85mol/l

but cant get B
answer is

0.143mol/l
 

Aerlinn

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Aug 29, 2006
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HSC
2007
You have 10g NaCl put into 200ml, which is equivalent to 0.171mol.
If that's the amount of mole of solute you have in 200ml, in 50ml you must have 0.171/4= 0.04275mol.
You're adding this 50ml to 250ml water, so you're concentration for solution B would be 0.04275/ 0.3=0.143mol/l

:)
 

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