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Dangerous lab experiment?

  1. Dec 20, 2003 #1
    Last semester we did a lab separating the components of a mixture. Part of the experiment involved subliming NH4CL (ammonium chloride) in an evaporating dish but instead of placing the dish in the hood (as outlined in the lab procedure), our class had to use open air bunsen burners. There were about 6 lab stations doing this all at once, so it got kind of smokey. Each lab station had about .8 grams of NH4CL that sublimed. (.8g x 6 labs = 4.8g total in the air) NH4CL has a lethal dose (LD50 30mg/kg) Which I think means 50% of rats died when given 30mg/kg. So per 1 kg of rat that was given (injected) 30mg, half died, right? So if the average person weighs about 140kg then the LD would be about 2.1g a person right? (30mg/kg*70kg=2100mg=2.1g) Since there were 12 people in the room (typical sized lab room) with no real ventilation, were we in any danger from breathing the ammonium chloride smoke? I asked the lab instructor if we were in any danger before the lab and he said no, there was probably more NH4CL in your last dinner than would be breathed in.
     
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  3. Dec 20, 2003 #2

    Monique

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    Just judging without calculating I would have to agree with your labinstructor. So exactly how much of the material were you subliming? You didn't mention that. *edit* you did mention, but you forget you can't just translate a rat figure to a human figure, you have to take variables into account such as different physiology and the rate of absorbance by the lungs in this case..

    To put you at ease: in the Netherlands (and other European countries too) we have the habit of eating very large quantities of licorice, the salty ones are my favorite! Which salt is it? Ammoniumchloride:NH4Cl, I eat lots and lots of it: it is safe :)

    Did you know that in a petition a vast majority of people advocated the banning of Dihydrogen Monoxide (DHMO), but it is still used everywhere today? Here is the website which informs people of this chemical: http://www.dhmo.org/facts.html

    What do you think, would you want to work in a lab which uses DHMO??
     
    Last edited: Dec 20, 2003
  4. Dec 20, 2003 #3

    Monique

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    The LD50 for DHMO: (IV-MOUSE) 25 MG/KG, same as the 30 for NH4Cl and I know DHMO is actually far more widely used..
     
    Last edited: Dec 20, 2003
  5. Dec 20, 2003 #4

    ShawnD

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    Yeah that DHMO is bad stuff. One time I was heating up some DHMO in the lab for a heat capacity experiment and the DHMO started bubbling violently. Some of the splashing DHMO got my hands and it burned the hell out of me [b(].
     
  6. Dec 20, 2003 #5

    Monique

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    I know, I too have to deal with it and the vapours create far worse burns as I was told by a fire-fighter..
     
  7. Dec 20, 2003 #6
    seems to be an ocean of evidence on the long term health effects of dihydrogen monoxide...don't want to water down the risks. BTW, there is a big DHMO dump site just west of Los Angeles.
     
  8. Dec 21, 2003 #7
    If you ever need to freeze a sample that's contaminated with DHMO, try DMSO (C2H6OS/dimethyl sulfoxide) as a cryoprotectant to prevent hexagonal crystal formation.
     
  9. Jul 16, 2004 #8
    water is actually poisonous, you can die from water poisoning from drinking too much water.
     
  10. Jul 16, 2004 #9
    Do you mean water (as in [tex]H_{2}O[/tex]) or something else?
     
  11. Jul 16, 2004 #10

    movies

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    Back to the NH4Cl question, were you just subliming the stuff for the sake of subliming it or were you collecting the sublimed material? Sublimation is a common method of purification. Either way, there are a lot more factors at play than just how much material was actually in the air. Most labs are very well ventilated, so most of the NH4Cl probably got sucked through the vents. Plus you have to take into account the concentration of the NH4Cl in the air. 4.8 g in a room that is, say, 10 m x 10m x 3m would give a concentration of 1.6*10^-8 g/mL. That's not much, considering your lung capacity is on the order of a 1000 mL. That's still less that 2 hundreths of a mg per breath.

    All told, you weren't in any danger.
     
  12. Jul 20, 2004 #11

    BobG

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    No, just be the third person to breath. :rolleyes:

    Actually, you have to compare the amount of NH4CL to the volume of the room, not the number of people. And the amount of air in the room that you'll actually breath. (I wouldn't be putting my face over to smell the fumes, though).

    And, in spite of its dangers, that DHMO is actually pretty good stuff for athletes. It has some great performance enhancing capabilities and is seldom even tested for in urine samples.
     
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