Chem

I'm pretty sure this should be a fairly simple conversion factor problem, but I'm getting bad results.
I want to go from molarity (mol/L) to density. Based on simply unit analysis, I figured that I could go in this direction:
mol/L x g/mol x L/mL = g/mL
With the appropriate units cancelling out. However, I am given a problem concerning KOH with a molarity of .886 and and a density of 1.06 g/mL. I decided to verify my method using these numbers, but they don't work out right:
.886 mol/L x 56.11 g/mol x 1 L/1000 mL = .049 g/mL
Obviously I didn't get the desired result, so what did I do wrong?


aboo boo boo boo?

what????? don't post things if ur not going to help and sorry i don't kno chem

The problem is that you don't know the percent KOH (it isn't 100%). If you did, then
[density g/mL x 1000 mL x (%/100)/molar mass] = molarity.

For example, we have all of the above numbers EXCEPT percent so we can calculate that.
1.060 g/mL x 1000 mL x (%/100)/56.11 g/mol]=0.866 M.
So percent KOH = 4.58%
I hope this helps you see you didn't do anything wrong. You just made the assumption that the KOH solution was 100% KOH and that isn't so, otherwise, there wouldn't be any solvent (water) there. =)

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asked by Tasha

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