posted by helllp .
I did a simple distillation and a fractional distillation to purify acetone. How do I determine the concentration of acetone? (Instructions say this is not a simple M=mol/L calculation).
My guess was to divide the volume of purified acetone by the volume of unpurified acetone (I started with). Is this right?
So you mixed a known quantity of acetone in water, distilled it, and now you know what about the acetone and water? What concentration of acetone are you looking for?
I know the initial volume of unpurified acetone (before distillation) and the final volume of acetone (after distillation)
hmm. I think you're leaving information out. Concentration is found by mass of acetone / volume liquid. Dividing initial volume by final volume leaves you with a unitless number - the percent of impurities maybe, and this isn't helping your case. You should have pretty close to straight acetone. You will need to deduct something out of somewhere. Do you have the initial or final purity of the mixes? Volume of the other liquid fractioned off? What other information do you have?
Yes, I have the volume of the purified acetone
-mass (of both unpurified and purified acetone)
-boiling point temperature (not sure if that's relevant)
I also have the density of the distillate.
I don't know what the initial and final purity of the mixes is, we were just told we were distilling "unpurified" acetone.
hmm. I'm a bit stumped. Why did the instructions say it is not a simple mol/L calculation? You must have the quantity of the acetone/impurity mix? At that point, you could simply say that you have so many grams / L of acetone. But, since it's not a straight calculation, I would research the question as to whether or not densities are additive - I believe density is additive. Figure out how to subtract the impurity and go from there. You can get the density of acetone from an MSDS on line.