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Topic: How do i find molality and mass precent given molarity and density?  (Read 7456 times)

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Offline daylees

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How do i find molality and mass precent given molarity and density?
« on: September 22, 2010, 10:51:32 PM »
An aqueous KNO3 solution is made using 87.8g of KNO3 diluted to a total solution volume of 1.60L.

Molarity =0.543M
calculate molality and mass precent (density =1.05g/mL)

i don't even know where to begin.
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Offline opti384

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Re: How do i find molality and mass precent given molarity and density?
« Reply #1 on: September 23, 2010, 02:15:06 AM »
What can you learn from the Molarity = 0.543M, density, and the total solution volume?
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Offline skbuncks

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Re: How do i find molality and mass precent given molarity and density?
« Reply #2 on: September 24, 2010, 07:49:56 AM »
It can help if you express the units of all the terms present.

Molarity = mol/L
Density = g/ml (or Kg/L)
Molality = mol/kg (mols solute/kg solvent)
Mass percent =  g/g %

So to calculate the molality you will need to know the mols of KNO3 and the mass of solvent (not the total mass).

skb
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