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Topic: Help with boiling point lab design?  (Read 2235 times)

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Offline luvana

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Help with boiling point lab design?
« on: September 10, 2014, 02:59:57 PM »
I'm doing a lab design, to determine boiling points of different concentrations of a solution. This is within organic chemistry, so obviously I have to choose an organic compound. The experiment will not be carried out in the lab, we are simply making an instructional lab design.

I thought about using Acetone solutions in my design. Would that work? Or is it better/more realistic with another compound? If so, which ones? Acetone is a dangerous compound, but then again, most organic compounds are flammable.

Another thing is that I am testing different concentrations. I would have to use dilute Acetone solution, and I am opting for three different ones. Does it matter which concentrations I go for? Could I say:
1 mol Acetone
2 mol Acetone
0,03 mol Acetone?
Basically, what range of different concentrations are best to use when doing an experiment like this?

I am in my last year in high school (Norway), and this lab design is being assessed. I just wanna deliver it without being in doubt of whether I did it right or not.

Thanks in advance!

Offline curiouscat

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Re: Help with boiling point lab design?
« Reply #1 on: September 11, 2014, 12:49:00 AM »
For one, solutions of acetone in  water (say) will never have a sharp boiling point. That only happens with pure components.

Two component mixtures have an Bubble & Dew Point instead of a boiling point.

Yes, acetone is very flammable. Using something like ethanol might reduce this risk. You could also choose an entirely non-flammable solvent. But then there's other considerations: cost, toxicity, BP low enough to not need high Temp.  etc.

Offline Enthalpy

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Re: Help with boiling point lab design?
« Reply #2 on: September 11, 2014, 04:26:05 PM »
Solution in water?

Could the solute be less volatile than water, for instance a solid? Then you wouldn't get its concentrated vapour over the solution, but purer water vapour which isn't flammable.

For glycol, polyglycol, propylene glycol, glycerine, heavier polyols... in water, extensive data already exists.

Offline luvana

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Re: Help with boiling point lab design?
« Reply #3 on: September 17, 2014, 02:45:02 PM »
For one, solutions of acetone in  water (say) will never have a sharp boiling point. That only happens with pure components.

Two component mixtures have an Bubble & Dew Point instead of a boiling point.

Yes, acetone is very flammable. Using something like ethanol might reduce this risk. You could also choose an entirely non-flammable solvent. But then there's other considerations: cost, toxicity, BP low enough to not need high Temp.  etc.

Thanks! I will use ethanol instead.
Another question: What is the most convenient way to express the different concentrations in this case? Apparently, you can express it in percentage composition, molarity, molality and mole fraction.

Offline zsinger

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Re: Help with boiling point lab design?
« Reply #4 on: September 17, 2014, 03:31:47 PM »
Be sure to use 100% EtOH to get results which are as accurate as possible.  This reagent is often times only available from a supply house, or made by the benzene azeotrope method.  Making it is NOT fun.
        -Zack
"The answer is of zero significance if one cannot distinctly arrive at said place with an explanation"

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