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Where does ethanol gas go in an enclosed space?

  1. Oct 21, 2016 #1
    What happens to ethanol vapor in an enclosed space like a room? Does it end up dissolving, or accumulating somewhere like the floor or towards the ceiling? If it does dissolve how long does it take?
     
  2. jcsd
  3. Oct 21, 2016 #2

    Simon Bridge

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    Short answer: depends.
    It may just remain in suspension. All other things remaining equal - once diffused, it spreads evenly through the room.
    You know, just like the water vapour in the room.
    And just like that vapour, it may also do other things - like condense, react or interact with other stuff in the room, or the walls...
     
  4. Oct 21, 2016 #3
    And around how long would it take for the fumes to dissolve?
     
  5. Oct 21, 2016 #4

    Simon Bridge

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    What do you mean by "dissolve"?
     
  6. Oct 21, 2016 #5

    jim mcnamara

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    This question seems to me to be part of: https://www.physicsforums.com/threads/etg-test-and-ethanol-vapor.890145/ [Broken]
     
    Last edited by a moderator: May 8, 2017
  7. Oct 21, 2016 #6
    Let me ask you this way. If I were in a standard sized classroom without ventilation, and say around 10-15 ml of hand sanitizer were used to clean the tables, how long would it take for the fumes to sink to the floor or disperse through the air? If I were still smelling the hand sanitizer, would that necessarily mean that I were inhaling the alcohol as well? I know this may sound like a weird question but its very important to me that I know the answer. Thanks for taking the time to help me with this BTW.
     
  8. Oct 21, 2016 #7
    It is.
     
    Last edited by a moderator: May 8, 2017
  9. Oct 21, 2016 #8

    PeterDonis

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    That other thread has been deleted. Please do not post the same question in multiple forums. Your posts here contain all the necessary information.
     
  10. Oct 21, 2016 #9

    jim mcnamara

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    Hopefully the the mentors will figure out how to bring everything together.

    Plus, you appear to be backing into a problem. What are trying to determine - it seems to relate to a fear that exposure to alcohol vapor will cause you to fail a test.
     
  11. Oct 21, 2016 #10
    How so? I'm new to this, so any feedback would be appreciated..
     
  12. Oct 22, 2016 #11

    Simon Bridge

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    .
    It is usually best just to get to the heart of the matter right away.

    Depends on the sanitizer. Light fumes would usually disperce through the room and get convected outside over a short time - like 5-10mins.
    There is a demonstration I do in classrooms involving diffusion of a strong scent in the still air... it typically takes less than a couple of minutes to get fill the room, but is not noticeable after 15mins.
    The concentration you intimate is much smaller than that.

    Depends - the scent is not necessarily carried by the alcohol.

    Why would this be such a concern?
    It is generally safe to be in a room with much higher concentrations of alcohol for much longer.
    Note: the importance to you is irrelevant - especially without reason - everyone feels their question is important.

    It is much better to present the problem you want to solve rather than dance around the topic like this.
     
  13. Oct 22, 2016 #12
    Thanks for the info. I take random UAs and one of the substances they test for is EtG, which is a byproduct of ethanol. The test is very sensitive and as I've recently learned cannot distinguish between alcohol consumption and incidental exposure.
     
  14. Oct 22, 2016 #13
    When you say light fumes, would that include any alcohol present in the vapor as well?
     
  15. Oct 22, 2016 #14

    jim mcnamara

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    IMO, these types of tests have legally mandated cutoff values. For example, poppy seeds have minute amounts of opiates. They are used in baking. Will eating a lemon tart with poppy seeds make you fail a drug test? This is the kind of question you are asking.

    The answer to poppy seeds is: they can be detected, but the interpretation of the result is defined legally. As is how the test is performed. A cutoff lower limit is mandated. Any value below that is considered negative.

    EtG can remain in hair for a long period - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3927158/
    EtG can be detected reliably in hair up to 12 weeks, again subject to several "if" statements.

    The answers depend on EXACTLY what the legal parameters are - not necessarily pure science. In these tests a 'false positive' is defined. There can be be false negative results in many kinds of assays like this due to the limits of detection:
    https://www.ncbi.nlm.nih.gov/pubmed/20975547
    There are a lot of tonsorial potions like mouthwash and after shave (Old Spice kinds of products) that have ethyl alcohol in them:
    Look for the word "ethanol": https://householdproducts.nlm.nih.gov/cgi-bin/household/brands?tbl=brands&id=16003196

    So unless you can be really specific about what we are talking about any answer we give will be a complete guess. Simon's explanation is good. Ethanol will diffuse to the point where humans can no long detect it in a room.

    How is the test performed? Hair? Blood sample?
    What is the cutoff for the defined lower limit of detection ?

    There MUST be somebody who knows this, like a lab technician at wherever you get tested, and can answer your question. We can only guess.
     
    Last edited: Oct 22, 2016
  16. Oct 22, 2016 #15
    Its a UA with a 100ng cutoff, which I took about 9 hrs after exposure. And what I want to know specific Ally is if someone used approximately 10-15ml of hand sanitizer to wipe down the tables in a 30x30x10 unventilated (no AC, no doors or windows open), around how long would it take for the alcohol to diffuse? I understand that any answer you provide will be an estimation.
     
  17. Oct 22, 2016 #16

    rbelli1

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  18. Oct 22, 2016 #17
  19. Oct 22, 2016 #18

    rbelli1

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    I'm pretty sure by "applied" they mean on the hands per the manufacturer's instructions. This product can also be semi-successfully "applied" orally. I suspect that the "false" positives were from this use. I highly recommend against that route of administration.

    BoB
     
  20. Oct 22, 2016 #19
    Actually studies have been done where subjects have tested dirty for EtG over the 500ng cutoff through inhalation of hand sanitizer. There are several studies that demonstrate this. The conclusions drawn from these studies were what caused me to ask my original question regarding what would ethanol gas in a space such as an unventilated room do, as I find myself in environments where ethanol based cleaning products were used and want to make sure that the gas disperses within a reasonable timeframe.
     
  21. Oct 22, 2016 #20
    But what I did want to know, is when it was mentioned above that "light fumes" would disperse within 5-10 min. is that referencing alcohol as well? And if not, how long would it take the alcohol specifically, to disperse, or sink, or do whatever its going to do other than just linger where it was just used?
     
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