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# basic math question

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### #1 Loris

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Posted 08 May 2009 - 11:47 AM

Hi,

I have a liquid that has a molecular weight of 108.16 g/mol. I need a final concentration of 4.5 x 10^-4 M. How do I find out the initial molarity (mol/L) of my liquid? Is there any information I'm missing?

Thanks!

### #2 Ahrenhase

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Posted 08 May 2009 - 03:20 PM

Hi,

I have a liquid that has a molecular weight of 108.16 g/mol. I need a final concentration of 4.5 x 10^-4 M. How do I find out the initial molarity (mol/L) of my liquid? Is there any information I'm missing?

Thanks!

it depends on how many grams are in your initial solution. g/mol is a measure of mass per quantity, mol/L is a measure of quantity to volume. A volume of feathers has a different mass than the same volume of lead.

### #3 K.B.

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Posted 08 May 2009 - 04:00 PM

Loris, you need the density of your liquid.