[firepants]

Hey! I just had a lab on simple and fractional distillation. We distilled mixtures of toluene and acetone... and I have some questions:

1. There was a difference in the initial volume we started with and the total volume recovered. Why was there a loss?
Is this something simple like vapour left in the condensor and the fractionating column is not accounted for when measuring the end products? I began with 50mL of the mixture, and ended up with 48.2mL (including the residue).

2. "A pure liquid has a constant boiling point, but a liquid with a constant boiling point is not necessarily pure". Why is this? I have no idea with this one.

3. Why is it important for the cooling water in a distillation apparatus to enter the condensor jacket at the lower and and exit at the upper end, and vice versa?
I know that the point of the condensor is to cool the vapourized substance in order for it to collect, but I didn't realize that it mattered which tubes were connected to which end.

If anyone can help me with these, it will be greatly appreciated! Thanks!

[Custos]

1. Where else might the liquid go? Acetone has a low boiling point and a reasonable vapour pressure.

2. I suggest you look up the definition of "azeotrope" for some clues.

3. The whole condenser has to be filled with flowing water to be effective, right? if water goes in the top and out the bottom does that happen?

[firepants]

Thanks so much!