[Benzoic Acid]

Hello, I had a lab using fractional and simple distillation, and so I have questions related to this. My prof. gave an unknown compound and we were to use fractional distillation to determine the two compounds in this unknown solution. There is a chart showing which compounds may be in the solution along with their boiling points.

My solution began to fractionate and form drops at 100-103 Celsius to form about 1.8 mL. Next at 114 Celsius, 1 mL was fractionated at this temperature. I know 1 portion of the mixture is water, because it gave lots of drops at 100-103 Celsius. However, the two choices I have for the compound that fractionated at 114 Celsius are:

Toluene - 110.6 C
1-Butanol - 117.2 C

I ran the experiment twice and it never went above 114, so must the second component of the mixture be toluene? I only had 2 drops or so that formed at 110, the rest were 114. The temperature would never go past 114.

Question 2:

This relates to that experiment as well and the unknown compounds were miscible. So I am wondering, is water miscible in toluene or even 1-butanol? I know butanol has an OH, so probably…

Question 3:

Does anyone have any examples of a fractional distillation vs. simple distillation graph? I'm curious as to if mine are correct or not. My simple distillation curve is very steep, while my fractional distillation is broad.

thanks

[FeLiXe]

It's always difficult to tell boiling points. I'd think the temperature on the thermometer will rather be too low than too high because it's kind of cooler up there (in theory it isn't). also the boiling point might be lower because it is still mixed a little bit with water. that would point to butanol. if you had a lot of heat down there and it distilled really fast the temperature was probably to high -> toluene.

you should be able to differentiate between 1-butanole and toluene by their smell. That's probably the easiest way ;-)
if it smells nasty like an alcohol, it's 1-butanole
if it smells even nastier it's toluene
(I can't really describe smells)

both are only partially miscible with water. But 1-butanol definitely better. I don't think you can have 2:1 mixture water/toluene. that points toward butanol.

fractional desitillation just means that you have many flasks at the end so can seperate fractions. simple destillation is when you just distill away one fraction and keep your product down in your first flask.

[plu]

fractional desitillation just means that you have many flasks at the end so can seperate fractions. simple destillation is when you just distill away one fraction and keep your product down in your first flask.

I am confused by this.  In both fractional distillation and simple distillation, there is only one receiver flask.  Fractional distillation is simply a more powerful distillation process that enables one to effectively perform a series of simple distillations at the same time.

[FeLiXe]

in my eyes fractional distillation means that you can easily switch receiver flasks and therefore collect fractions.

or do you mean that you have a column that helps you separate the substances?  So the steam would first go through the column and then into the cooler. that I would call rectification.

those terms are the direct translations from German. but maybe you use them in a different way in English.

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well anyway if you do have a column then you should have narrower temperature ranges for the substances. I don't think you can separate water and toluene without one actually. the graph should be steep in some parts (when substances come) and flat in between.

edit: I mean: the other way around: steep temperature rises when no substance comes and flat when they come

[pantone159]

Fractional vs Simple distillation means with a packed column vs no column.

As far as smells, if you are familiar with the smell of model airplane glue, that is toluene.

[FeLiXe]

ok, I have to remember that

is there a specific English word to differentiate between having one and many receiver flasks?

[Benzoic Acid]

Hmm, maybe I heated too fast and water is not one of the substances. I never noticed a nasty smell.. so it must be 1-butanol for the second substance...how chemistry like, lol. "Forget the boiling point! What does it smell like!?"  But the comments have helped.


Also instead of starting a new thread I will probably have a few more questions. Although this isn't related to distillation, it is a lab orientated question.

A sample of naphthalene, which should be pure white, was found to have a grayish color after the usual purification procedure. The melting point was correct and the melting point range small. Explain the gray color

Could this gray color be from decolorizing charcoal or would residue from this change the mp?

thanks!