As part of a small experiment, I'd like to boil bioethanol (I believe it should boil at 80 degrees).

Would the resultant gas be safe (to humans)?

Presumably it would be quite flammable?

In small amounts, would it safe to burn the gas as it is being emitted?


1 Answer 1


Bioethanol is the same thing as ethanol and its behaviour as the major compound is identical. There would be differences in minor or trace impurities or denaturating additives (these depend on the source and country). Note that bioethanol for fuel purposes is implicitly assumed to be denaturated as well.

Define safe. As it could be very safe and very dangerous, depending on scenario.

Ethanol boils near $\pu{78 ^\circ C}$ , forming ethanol vapor as the gaseous phase of ethanol. Its inhalation has much stronger effect with much faster raise, compared to drinking the same amount. As it gets through large lung surface directly to tissues, body liquids, blood and brain. It can be very dangerous due difficult control of the level of exposure.

Yes, it is very flammable, forming explosive mixture with air in range $\pu{3.3 - 19} \text{ vol %}$ of vapor. In countries where personal alcohol distillation is prohibited, badly maintained illegal distilleries sometimes ended in violent explosive destruction of the room (or the house).

Note that ethanol vapor is used in ethanol bases campsite/outdoor burners where ethanol is being evaporated and gaseous ethanol serves as the gaseous fuel in conventional gas burner. It is simpler/cheaper than petrol/spirit burners, has less issues than LPG in air traffic, but has less heating power than both petrol or LPG ones.

  • $\begingroup$ Thanks! I should have clarified, I would be boiling very small amounts, say 10 or 20ml. I certainly wouldn't be looking to inhale it. If you had a naked flame near the source of the rising gas, would that safely burn it off (minus 'explosion')? Nothing would be contained. By safe I'm just trying to avoid any vapors that would irritate/poison people (or get them drunk) or that would trigger a large fire/explosion. I never suspected that would be the case when dealing with small volumes in an open container, I just wanted to be sure... $\endgroup$
    – Ben Logan
    Sep 11, 2023 at 9:21
  • $\begingroup$ As the general precaution, no open flame nearby boiling or hot ethanol, unless the ethanol burning is the primary reason. If you remember school demonstations of explosion of bubbles, filled with hydrogen and air/oxygen, you can have rough idea of explosion intensity of comparable volume of ethanol/air mixture. $\endgroup$
    – Poutnik
    Sep 11, 2023 at 9:26
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    $\begingroup$ Thanks. I should have clarified - a 'small' explosion is indeed the desired outcome! I will start with VERY small volumes and build up from there until I deem the effect reasonable enough to be entertaining, while still within safety margins! Thanks for taking the time to help! $\endgroup$
    – Ben Logan
    Sep 11, 2023 at 9:30
  • $\begingroup$ So, Ben Logan, what is your question? $\endgroup$
    – Maurice
    Sep 11, 2023 at 14:24
  • $\begingroup$ I think it has been answered - ambiguity around safe, obviously, but agreement that in small amounts and in a well ventilated space, the gas resulting from boiling bioethanol is safe to humans and flammable, but not to the extent that you couldn't burn a small amount of it safely. $\endgroup$
    – Ben Logan
    Sep 11, 2023 at 21:44

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