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  1. #1
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    Preserving Dry Ice?

    Hi,

    This may sound like an odd question but I am in need of the answer. Would vacume sealing dry ice keep it longer? I mean those kitchen sealers and bags that suck almost all of the air out and then seal it. The bags are pretty tough so I think they could stand up to the cold. Any input would be great.

    Thanks
    Jeff
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  2. #2
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    No. Air is not the enemy here temperature is.

  3. #3
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    I'm pretty sure you'll need to keep the dry ice's surronding enviroment under -109. Otherwise it will sublimate.

    I don't think putting it in a vacumn would do the trick.

    Edit: Blue beat me.

  4. #4
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    Hi,

    Thanks. It will be in a cooler as well but I was under the impression dry ice is also adversely affected by air. Its mainly for camping and will be in the cooler to keep things frozen..

    Jeff
    Last edited by Xoopiter-Jeff; 05-06-2005 at 11:34 PM.
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  5. #5
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    And putting it in the freezer won't do much.

    The best way is to wrap it up in newspaper, put that in a styrofoam box, and put that in the freezer. That will only delay the process of sublimation though (the process of a solid turning directly into a gas without going to a liquid state first).
    Thanks chemistry class!

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  6. #6
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    The container should not be sealed absolutely airtight. It needs to be leaky enough for the excess carbon dioxide to escape as it evaporates. If it is sealed too tightly it can rupture or explode when the pressure gets too high.

  7. #7
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    That's right Disgruntled.
    Back in the day we used to make a very impressive explosion by putting a little piece of dry ice in a 2 litre pepsi bottle with a couple of drops of water and putting the cap on tight.

    It made a fantastic noise but didn't do any damage to anything.

  8. #8
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    From a thermal physics perspective

    You have
    Q - which is heat
    K - constant coefficient of thermal conductivity (depends on material)
    A - area of material
    T - temperature in Kelvins
    d - distance (thickness) of material

    Put together to have

    Q = (KA[delta]T)/(d)

    *delta = change in

    Basically, that just says that if you put lots of wrapping around the dry ice and keep the outside temperature as close to the dry ice temperature (the delta t), then less heat would be transfered (in physics, there's no numerical representation of "cold"), less heat being transffered would mean that it'll last longer. This transfer would keep on going until everything (in theory) reaches thermal equilibrium

    =]
    Last edited by Oakii; 05-07-2005 at 12:02 AM.
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  9. #9
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    Originally posted by blue27
    That's right Disgruntled.
    Back in the day we used to make a very impressive explosion by putting a little piece of dry ice in a 2 litre pepsi bottle with a couple of drops of water and putting the cap on tight.

    It made a fantastic noise but didn't do any damage to anything.
    Yea that is great fun! When I was in high school we tried it with all sorts of bottles and the bang is incredible. There was always nothing left over after the blast so no evidence .

    Jeff
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  10. #10
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    Like blue said the enemy is temperature, the ice would melt and let out some air bubbles that were trapped inside it.
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  11. #11
    Originally posted by blue27
    That's right Disgruntled.
    Back in the day we used to make a very impressive explosion by putting a little piece of dry ice in a 2 litre pepsi bottle with a couple of drops of water and putting the cap on tight.

    It made a fantastic noise but didn't do any damage to anything.
    Awsome! I need to try that

  12. #12
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    If you do try it make sure you stand well back from the bottle after you put the cap on.

  13. #13
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    Originally posted by blue27
    That's right Disgruntled.
    Back in the day we used to make a very impressive explosion by putting a little piece of dry ice in a 2 litre pepsi bottle with a couple of drops of water and putting the cap on tight.

    It made a fantastic noise but didn't do any damage to anything.
    where did you get dry ice from lol?

  14. #14
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    You can buy dry ice from all sorts of places over here....

  15. #15
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    Re: Preserving Dry Ice?

    Originally posted by Xoopiter-Jeff
    Hi,

    This may sound like an odd question but I am in need of the answer. Would vacume sealing dry ice keep it longer? I mean those kitchen sealers and bags that suck almost all of the air out and then seal it. The bags are pretty tough so I think they could stand up to the cold. Any input would be great.

    Thanks
    Jeff
    Easy, pack it in dry ice

  16. #16
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    Re: Re: Preserving Dry Ice?

    Originally posted by Webdude
    Easy, pack it in dry ice
    Easily the smartest thing I've read in this thread.

  17. #17
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    Originally posted by ilyash
    where did you get dry ice from lol?

    At the hotel I worked at we would often get things packed in dry ice.
    You don't see it very much any more.

  18. #18
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    I get it at a welding place. Its $10 Canadian for 10 lbs (which is a big cooler full). Pretty cheap and lots of fun but be careful.

    Jeff
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  19. #19
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    Get a co2 fire extinguisher, wrap an old pair of overalls over the end and blast the co2 through for 5-8 seconds. There should be enough there for a fair few bangs
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  20. #20
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    This is the best way to preserve (increase the shelf life) of dry ice.

    1. Get the largest metal esky available.
    2. Wrap the dry ice in newspaper
    3. Cover the entire floor of the esky with the wrapped dry ice
    4. cover the dry ice with a thick layer of crushed ice.
    5. Fill the remaining space with cans of my favourite beer. VB
    6. Empty the remaining ice over and around the beer.
    7. Place the esky in a secure shaded area.

    Come to think of it this method probably won't do much for the dry ice but is great for the Beer

    The dry ice is too cold for cooling purposes, unless of course you want everything frozen. However having the ice on top of the dry ice will prevent the goods from freezing, and the ice will last far longer. Of course with the beer being stored at such a low temperature, they probably won't last all that long, for this reason one should never camp to far from a ready supply (pub, general store, off licence) of beer.

    Doc
    Last edited by TheDoctor; 05-07-2005 at 11:31 PM.
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  21. #21
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    I know that liquid nitrogen is kept in special airtight coolers with a vent for gas that boils off. Maybe one of these : http://cgi.ebay.com/ebaymotors/ws/eB...category=66470 : if you're dealing with a lot of it

  22. #22
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    I found some videos on dry ice bombs used underwater.

    ** Warning some mild profanity is used in the videos**

    http://www.putfile.com/media.php?n=shookhouse

    http://www.putfile.com/media.php?n=science3


    Jeff
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