Boiling HF

Discussion in 'Chemistry' started by michelle24, Apr 30, 2013.

  1. michelle24 Registered Member

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    Since hydrofluoric acid will eat most metals, how do you boil it? I tried to boil water in a water bottle, but it melted the bottle. Are there any high temperature bottles or containers?
     
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  3. arauca Banned Banned

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    You boiled water in a bottle , and it melted the bottle .. There is something wrong , I think the bottle will not melt as long you have water in the bottle.
     
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  5. youreyes amorphous ocean Valued Senior Member

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    well if you boil the water in a glass bottle, it should crack from extreme temperature, but that water boiling temperature would be much higher than the point at which glass cracks.

    If he is talking about a plastic bottle melting, that makes sense.

    HF should be stored in plastic bottle, since it dissolves glass.
     
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  7. leopold Valued Senior Member

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    wrong.
    people have been "home canning" for a very long time using glass jars under pressure which raises the boiling point of water.
    yes, they were regular glass jars, not some special heat resistant glass like pyrex.
     
  8. rpenner Fully Wired Staff Member

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    4,833
    Fluorine chemistry laboratory practice is a highly technical subfield of chemistry. It appears you lack the prerequisites for safe and effective handling of these materials. Do we need another generation of "fluorine martyrs?"

    http://pipeline.corante.com/archives/2010/02/23/things_i_wont_work_with_dioxygen_difluoride.php
    http://en.wikipedia.org/wiki/Fluorine#History
    http://en.wikipedia.org/wiki/Fluorine#Hazards
    http://en.wikipedia.org/wiki/Hydrofluoric_acid
    http://en.wikipedia.org/wiki/Hydrogen_fluoride
     
  9. Captain Kremmen All aboard, me Hearties! Valued Senior Member

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    Since you failed in your "boiling water" experiment,
    I would perfect that first before you progress to HF.

    Plus.......................
    Girls should press flowers, not boil Hydrogen Fluoride,

    In any case, it is a gas at standard room temperature, so it is already boiled.
    bp 19.5 degrees Celsius.
     
  10. youreyes amorphous ocean Valued Senior Member

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    you just cut my sentence in half and of course it is wrong now.

    actually my mistake was in wording, I meant the boiling point of water is much lower than the temperature at which glass cracks.
     
    Last edited: May 1, 2013
  11. exchemist Valued Senior Member

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    6,624
    The boiling point of HF is below room temp, so plastic bottles will do fine.

    Regarding "eating" metals, I think you will find that anhydrous HF, as used in the oil industry for alkylation for example, is not corrosive towards metals. But if it gets wet, then watch out! That goes especially for the moisture present in human tissue of course.
     
  12. arauca Banned Banned

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    At high concentration HF form a bi fluoride HFFH is formed and I believe is liquid
     
  13. Pete It's not rocket surgery Moderator

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    You don't boil it. You don't do anything with it. You leave it alone. It is dangerous. It is likely to kill you.
    This question is as inappropriate as a question about making a fertilizer bomb.
     
  14. youreyes amorphous ocean Valued Senior Member

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    Had they known this knowledge, the bomb making process would be on its way for sure, a do-it-yourself idiots guide to be exact. A mirror of the "learned from internet for sure" Boston terrorists schemes, and no help whatsoever from AlQuida.
     
  15. exchemist Valued Senior Member

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    Interesting, but I could not trace any references to this. See here for example: http://en.wikipedia.org/wiki/Hydrogen_fluoride

    Can you direct me to a source for this bifluoride, or are you perhaps thinking of the hydrogen difluoride anion, which contributes to the exceptional acidity of HF?
     
  16. Pete It's not rocket surgery Moderator

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    National security is irrelevant; this is about Michelle's personal safety. Heaps of people can and do learn this stuff, in an appropriate environment, with the right safety equipment and supervision.

    Boiling your own HF is about as good an idea as removing your own appendix. Sure, you can find an online how-to, but if someone posts a question about what to do if they were separating the appendix from its mesentery, and now there's spurty red stuff blocking their view... the only advice I'm going to give them is to apply first aid and call an ambulance.
     
  17. exchemist Valued Senior Member

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    Indeed. The thing that makes glass crack is a thermal gradient, because this causes different areas of the glass to expand to different degrees, creating stresses. If you gently and evenly heat it, it does not crack. (I had fun at university on a glass-blowing course, to train me to build a vacuum line, and quickly discovered how much thermal stress glass can take without cracking.)

    One thing that helps if you want to boil things in glass, as chemists do all the time of course, is to use a thin-walled vessel. This reduces the stresses that can build up in the glass and avoids cracking. But don't try this with HF of course, since it dissolves glass.
     
  18. youreyes amorphous ocean Valued Senior Member

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    so your saying if you put water in a glass jar in an oven at 900F, it will not crack? Obviously no oven will evenly distribute the heat to the glass material and obviously some part of the glass are thinner and some parts are thicker, therefore it will indeed crack based on temperature gradient as you have said, question is only time. Or what am I missing here?
     
  19. Pete It's not rocket surgery Moderator

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    *Gently* and *evenly*.
    Put the jar of water in a room temperature oven. Slowly raise the heat to 900F. How slowly? Not sure. Might take an hour? Slowly enough that all parts of the jar are always close to the same temperature, so there is very little temperature gradient. The water will boil away. The glass won't crack, according to exchemist.
    Makes sense to me.
     
  20. exchemist Valued Senior Member

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    Do you honestly think directly plunging a glass jar at room temperature into an oven at 900F, when it contains a substance that boils at 212F - and thus cannot get any hotter, regardless of how hot the outside of the jar becomes - is an intelligent way to heat it "gently and evenly"??

    Neither do I. See also Pete's reply.

    But a thin-walled vessel can boil water, even if heated by a direct flame. Old-fashioned coffee percolators worked like this. The explanation is that the thinness of the walls allowed the boiling liquid to carry away the heat from the flame fast enough to prevent an excessive thermal gradient. Note they were spherical in shape with no corners, so even thickness throughout. If you try the same thing with a milk bottle or a glass jar, then of course it will crack, because the glass is far thicker, especially at the corners, creating uneven expansion.
     
  21. origin Trump is the best argument against a democracy. Valued Senior Member

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    Leave HF alone. This is really dangerous stuff. I am aware of people in my company that have lost their lives from HF. I personally know one chemist who unknowingly spilled a drop on his finger and was not aware of it until later that evening when it started to dissolve the bone in his finger tip - not fun at all. I wouldn't touch the stuff with a ten foot pole.
     
  22. wellwisher Banned Banned

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    HF can be stored in plastic containers such as polyethylene. So if I had to boil it, I would first pull a vacuum to lower the boiling point. This way I could make use of PE containers and tubing.
     
  23. arauca Banned Banned

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    very good point , use vacuum.

    But the question remains why would you want to boil HF.
    Then the question can be also that he have a very diluted HF. and he wants to concentrate the diluted HF
     

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