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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: etruttan on May 23, 2008, 06:57:46 PM

Title: % solution issues
Post by: etruttan on May 23, 2008, 06:57:46 PM

I was wondering how you would find the # of grams of a solute in a solution.  If I have a 4% solution, where the solvent is water and the solute has a density of 3g/cc, how may grams are in 500ml?  I guess my question is, does the density of the solute matter?  Would it always be 20g regardless of solute, or would it be 60g for this solute?

Title: Re: % solution issues
Post by: Borek on May 24, 2008, 04:52:27 AM

What 4%? w/w? w/v?

Assuming it is w/w - it is enough to think about definitions. 4% means that 4% of the solution MASS is solute. What is mass of 500 mL of solution that has density of 3 g/mL?

Title: Re: % solution issues
Post by: RBF on May 25, 2008, 10:27:09 AM

You will need to know the density of the solution, which is not given in the information.  At a concentration of 4%, it will be fairly close to the density of water, but depending on the precision needed, the density of the solution will need to be determined.

Title: Re: % solution issues
Post by: Borek on May 25, 2008, 11:22:32 AM

Geez, it was solute density, not solution density. My mistake.

Density of solute doesn't matter. Density of solution does.