Morning, All.

Discussion in 'Chemistry' started by Doc Braun, Apr 4, 2011.

  1. MacGyver1968 Fixin' Shit that Ain't Broke Valued Senior Member

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    7,028
    Is it a drama or comedy? You could edit some stock footage of a nuclear explosion going off inside the beaker. Just an idea.
     
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  3. Doc Braun Registered Member

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    Yes, they're good. And I probably will buy or make one, one of these days. They are basically just a hot plate with a fan, and you run mineral oil on to the plate and the fan disperses the resulting smoke.

    Our amateur live theatre hired one a while ago for a "London night" scene. There are also fog machines that produce large quantities of dry ice fog, but it tends to stay low and doesn't persist for very long unless it's constantly replenished. Also, the air has to be slightly humid for the fog to form. Humidity plus hot lights makes for an uncomfortable experience on a small set. My actors would be working for free, and they might kinda lose their enthusiasm for the job...

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    I probably should mention that even though I only make films in the amateur sphere, I am very familiar with all the various tools of the professional trade. Just can't afford them.

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  5. Doc Braun Registered Member

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    LOL! Like when the mad scientist in Bugs Bunny cartoons drops a single drop of something into a beaker of fluid and the mushroom-shaped cloud rises out of it. Yeah, I love that.

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    But, no, it's a drama. If I went the compositing route, I'd probably use After Effects, or film something seperately and green screen it in.
     
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  7. Trippy ALEA IACTA EST Staff Member

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    I'll have to see if I can track it down, as I don't recall the specifics, but there's the explosion in a test tube, which is relatively safe.

    I seem to recall that it involved sulfuric acid and glycerol. The setup was that you poured them so that they formed seperate layers, and then dropped crystals of potassium permanganate in them (there may be more to it than that, it's been nearly ten years since I trained as a chemistry teacher, and I haven't repeated the experiment since then, but I'm sure I have the details at home).
    There's a spectaclur flash of light in the test-tube, and a rather spectacular explosive noise, and quite a bit of heat can be generated, so some care is neccssary. And you only want to add a single grain, because each grain added nucleates its own even IIRC.

    I'll see if I can track down some more info when I get home.
     
  8. Doc Braun Registered Member

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    Yipes! Thanks, Trippy, but I don't think I'll be doing that one! Certainly sounds impressive, but I don't want anything acidic near my actor, and definitely not h2so4!!

    Still, having said that, it does sound like a fun effect. Maybe I can incorporate it into the film somehow, and film it outside without actors...
     
  9. adoucette Caca Occurs Valued Senior Member

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    I didn't include that one because of the safety issues, dealing with sulfuric acid is not something I'd want to do on a movie set.

    http://www.youtube.com/watch?v=T15kCaPDT9I

    Note what happens when he dumps the cylinder at the end of the video.

    As far as including it, it's really not that impressive unless you turn off the lights, or when you dump it out, but again, I'd not recommend this one because of the potential for screw ups (like notice he points out that the Sulfuric acid will boil if you don't add the ethanol carefully, well that's a screw up you really don't want to have happen!)

    Arthur
     
  10. Doc Braun Registered Member

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    35
    I agree! He's a trained man, yet even he seemed nervous. It'd be nerve-wracking on a film set, (which is nerve-wracking enough at the best of times).
     
  11. adoucette Caca Occurs Valued Senior Member

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    He was nervous....

    He was doing that with out gloves on and when he poured the Alcohol in he put it in a bit fast and you could see that the acid started to boil a bit.

    A bit more and it would have erupted out of that cylinder and spoiled his whole day.

    On the bright side, the video would have probably gone viral.....
     
  12. Trippy ALEA IACTA EST Staff Member

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    That wa sthe reaction I was thinking of. :Shrugs: I did it in a hand held test tube, no gloves. I remember it being more spectacular than that, but in the dozens of times I did it, not once did it catch on fire on me like that when I disposed of it :shrug: but then, he used multiple crystals, where I only added one or two at a time.

    It impressed my senior chemistry class at any rate.
     
  13. Trippy ALEA IACTA EST Staff Member

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    Yeah, it's one of those experiments that you need to be confident when you prepare it, and carry it out, otherwise you're going to screw it up.

    I may have pre-prepared my Ethanol/Acid mixture, and it may have had time to cool, which may have been why I got different results.
     
  14. scifes heckle the snobs Valued Senior Member

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    2,561
    ooooooh...
    aaaaaahhh...
    very nice, never thought when chemicals burn together they give you some time to withdraw your hands, i always thought they'd goBOOM as soon as the first two molecules get in contact.
    also, how come does the reaction in the second video "builds up" that cone thingy on itself?
     
  15. adoucette Caca Occurs Valued Senior Member

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    7,829
    The Chromium Oxide formed from the exothermic reaction of the Potasium Dichromate is just a lot less dense, and so as it is produced it creates the cone.

    Watch as it burns, the reaction proceeds relatively slowly and there is not that much energy to push the new lighter material that far away, so given that the cone shape is pretty much what you would expect.

    Here's an even better cone:

    http://www.youtube.com/watch?v=Ula2NWi3Q34&NR=1&feature=fvwp

    Arthur
     
  16. Stryder Keeper of "good" ideas. Valued Senior Member

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    13,101
    "Dry Ice" (Solid state Carbon Dioxide) is usually the method used in films to generate the "Smoking formula". Plonk a pellet into water at room temperature and it will give out the smoke effect from the beaker. (Obviously handle Dry Ice with care considering it's going to be at at least -60°C, so some gauntlets are good to have for handling or use tongs.)

    a quick look online pulled up this URL for Australian Distributors, You can always give them a buzz, Identify what you need and the price, they might even clue you up on how to handle it if you don't search online.

    Otherwise there is Magnesium, however this is more of a pyrotechnic display. Especially if you happen to use it with the Dry Ice (If you use magnesium, don't have a Carbon Dioxide fire extinguisher at hand as it obviously reacts further with CO[sub]2[/sub] [have a look at uncontrollable magnesium reaction in dry ice ])

    Otherwise if you are "filming" the reaction, why not look at a CGI method of implanting a fictitious reaction over the filmed event. (That's the safe way of doing it)
     
  17. adoucette Caca Occurs Valued Senior Member

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    7,829
    If you have any old boxes of Ex-Lax laying around you can use that as it was the main ingredient.
    It was widely used as a laxative, but the FDA changed it's designation from "generally safe and effective" a few years back after some negative testing on rats.

    I checked my medicine chest and sure enough I had some old enough to still be made with it.
    If you find some just crush it up and dissolve it in water and it will work just fine.

    Arthur
     
  18. scifes heckle the snobs Valued Senior Member

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    2,561
    aww, just as i was seeing it's "walls" get higher and thought to myself "maybe we can use this on a larger scale to build-" when it caved in..

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    i get it the soot that builds up is not strong or sticky but light and fluffy?
     
  19. Trippy ALEA IACTA EST Staff Member

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    Actually, it occured to me this morning there are two reasons that the mixture never caught fire on me.

    I was using smaller quantities than was used in Arthurs video - as mentioned, I was conducting it in a test tube, and I was tipping it into a sink full of water as a saftey measure to prevent the mixture from catching fire.

    Add the acid to the water, not the water to the acid

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  20. Doc Braun Registered Member

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    Yes, I've looked at all those solutions, Stryder, thanks. There's a dry ice supplier not far from where I live, too.

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    EDIT: I've been speaking with a chemistry student here who also happens to have an interest in film effects, (his sister is involved in a film club). He suggested using the dry ice trick, but with one major difference. You don't immerse the dry ice in the fluid.

    He said to get a plastic bucket with a tight lid, fill it with warm water, and run a hose from a hole in the lid to a small hole drilled in the beaker, just above the level of the coloured fluid in it. That way, the fog would come from the back of the beaker, (disguised by the actor's hand), and appear to be rising from the surface of the fluid without the usual attendant bubbles and "popping" of the fog.

    I'm going to try that.
     
    Last edited: Apr 6, 2011
  21. Doc Braun Registered Member

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    35
    We don't have ex-Lax here, Arthur. Our most common laxative product is called "Laxettes", and is in the form of a mini bar of chocolate. That probably wouldn't work.
     
  22. adoucette Caca Occurs Valued Senior Member

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    7,829
    To do what you oughta, add acid to wata...

    Arthur
     
  23. Trippy ALEA IACTA EST Staff Member

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    I wonder if it might be easier to adapt a vacuum filtration flask - or find one with a lower (more useful) point of entry.

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