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TechnoratiMolarity Calculation
Submitted by ecalcutt on 8 July 2005 - 4:46am.
The following question appeared in a recent chemistry exam of mine. I am absolutely positive that I reached the correct answer, but my professor will argue otherwise. Please help confirm my conclusion.
"In order to prepare a standard 1.00 M solution of oxalic acid from H2C2O4 * 2H2O (molar mass = 127.07 g/mol), 3.152 g of oxalic acid dihydrate should be dissolved in......"
This was a four-choice question (however, I only remember two--my answer and the professor's).
A) enough water to make 25 mL of solution
B) 25 g of water
I concluded that "A" was the right answer. (I don't want to influence a decision, but we were not given the temp. of the water, nor the density) Any help would be GREATLY appreciated.
You'd want the solution to come to a volume of 24.8mL, if you really want to be picky.
I think I would have said A; arguably the oxalic acid will take up zero volume when dissolved in water, so A and B are the same answer, but A would be more correct, I say.
I'd make sure somebody else on here agrees though.
I have been known to make just a few mistakes.
A) is the correct answer if you go for molarity (moles of solute in volume of solution)
B) is the correct answer if you go for molality (moles of solute in mass of solvent)
1.00M usually is the abbreviation for molarity, so answer A) is correct