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Boiling solvents

  1. Jul 8, 2007 #1
    I'm planning on studying chemistry in university next year and although I know a good bit of inorganic and organic chem theory I have very little practical lab experience.

    I want to get a feel for simple procedures like dissolving chemicals in solvents and recrystallizing etc.

    I want to test out solubilities with common solvents like isopropyl alcohol, methanol, acetone etc.

    Is it safe to bring solvents like these to the boiling point in order to dissolve chemicals into them? Alcohols aren't as volatile as acetone so I wouldn't be as worried working with them but is it dangerous to bring a solvent like acetone to the boiling point? I'd imagine it would create alot of vapours and there would be the possibility of the vapours hitting the stove and igniting but how high is the risk of something like that happening?

    What safety procedures should I take if I was to boil a volatile solvent like acetone?
     
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  3. Jul 8, 2007 #2
    I don't have a hotplate at the moment so I used a frying pan with cooking oil as a replacement but something strange happened.

    I placed some powder which is insoluble in acetone at low temperatures at the bottom of a 150ml borosilicate beaker and poured about 4 times the amount of acetone on top of it.

    As the temperature raised slightly violent bumps started to occur. Big clumps of the powder solid at the bottom started shooting up whenever a bump happened. I picked up the beaker and it continued to bump once or twice even after if was off the frying pan. Whats this all about? Is it because I'm using cooking oil or is it because the beaker is way too small for the frying pan?
     
  4. Jul 9, 2007 #3

    chemisttree

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    You discovered what is known as "bumping." This kind of stuff is one of the primary reasons that people burn down their homes trying to do dangerous chemistry without proper equipment, controls or training. You should wait till you are at University before continuing any further. With proper equipment and training this stuff is trivial, so there is NO ADVANTAGE to you practising at home before you attend University...

    By the way... what kind of fire extinguisher were you using?
     
  5. Jul 9, 2007 #4

    mrjeffy321

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    In general, I do not boil volatile solvents like these … and if I ever wanted to, I would certainly not do it inside on my kitchen stove.
    Boiling these solvents, of course, is somewhat of a fire / explosion hazard, not to mention the fumes it puts into the air which are also not a good idea to breathe.
    So if you really have to do these types of experiments, do it outside and using the proper equipment (both to perform the experiment and in terms of safety). But why not, instead, use less volatile solvents…like water for example, much safer and will still allow you to dissolve and recrystallize substances.

    It sounds like your boiling solution is “bumping” (as “chemisttree” already said), it is not boiling evenly and this can cause problems for you, especially considering the types of solvents and heat source your using, since it may result in your container tipping over or breaking (and in the process spilling out its contents).

    I would tend to disagree with that statement, unless the “this” you refer to is specific to the thread at hand and not at-home-chemistry in general.
     
  6. Jul 9, 2007 #5
    Yeah I'll leave boiling volatile solvents and things like that until I'm in college. I didn't even have a fire extinguisher just a wet towel.
     
  7. Jul 9, 2007 #6

    Bystander

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    Have your acceptance speech prepared for the Darwin Awards ceremony --- these awards are presented immediately upon your completion of worthy efforts. Acceptance speeches traditionally begin with the phrase, "Oh, sh*t!"

    Leicester, http://search.yahoo.com/search?p="l...istry"&fr=yfp-t-482&toggle=1&cop=mss&ei=UTF-8 , is cheap, Amazon lists a number of similar histories, http://www.amazon.com/Historical-Background-Chemistry-Henry-Leicester/dp/0486610535 , and you could do yourself a big favor reviewing the mortality rates associated with the "genetic" approach to learning chemistry.
     
  8. Jul 9, 2007 #7
    You've lost me bystander. I didn't understand a single sentence of what you just said. Whats the Darwin Awards ceremony?

    What do you mean by the "genetic" approach to learning chemistry?
     
  9. Jul 9, 2007 #8

    Bystander

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    "The genetic approach" to learning anything is to duplicate the actual historical development, pitfalls, pratfalls, and all (tasting thallium and beryllium salts, cooking gunpowder, using the fluorescence of fingers to locate X-ray beams). This may be contrasted with "the systematic approach," in which the subject is approached on the bases of its relationships to other subjects (in the case of chemistry, physics, life sciences, geology, etc.), and the identified principles relevant to the field.

    "Darwin Awards?" Do a little "googling," you'll find out what you need to know. It suffices to point out that what you don't know can hurt you, and that unstructured investigations can be fatal.
     
  10. Jul 9, 2007 #9
    Ah I get you. I see your point. Although it was less than 20 ml of solvent I was boiling I should still leave that kind of experimentation until I'm in college.
     
  11. Jul 9, 2007 #10

    Bystander

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    "20 ml?" Third of a mole. Times three moles CO2 plus three moles H2O --- 600 kJ, give or take my mental arithmetic, which you can compare to 200 J for the average firecracker. Good decision. You were fortunate.
     
  12. Jul 14, 2007 #11
  13. Jul 14, 2007 #12
    I was wondering how much a reflux setup would minimize the risks involved in heating solvents. Assuming the setup is sealed and no vapours can escape is there any way the fumes can ignite other than exceeding the auto-ignition temperature of the solvent?
     
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