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The Self-Carving, Exploding Pumpkin

Just call it the Halloween After-Glow. No, it’s not the warm feeling you get in your heart when you think of all of those darling little Trick-or-Treaters or think of the fun kids had opening their candy. The “After-Glow” refers to the light coming from inside the pumpkin after the kaboom! Hundreds of chemistry teachers from across this great land of ours joined together yesterday to share their favorite Halloween science demonstrations.

VIDEO: Steve’s Exploding Pumpkins

Here’s your next question… How do you do it? Since this is a classic chemistry teacher demonstration, it’s best to consult your favorite chemistry teacher or let your fingers do a little “googling” to research the various ways to produce the small amount of acetylene gas in the pumpkin… or just read through the comments below.

Editor’s Note: This experiment was presented in this forum for educational purposes only.  We DO NOT recommend trying this experiment in the classroom unless you have had proper training to do so.  Please note that Steve Spangler Science takes no responsibility for comments posted on this site.

On a personal note, I know that Steve practiced this experiment at least 20-30 times with trained professionals, in a controlled environment, before presenting the experiment on the air.  Even for television, the experiment was performed with safety personnel and fire officials on-site.  This is not a do-it-yourself activity.

Please have a safe and happy Halloween – the Editor

14 replies
  1. Joyce Howard
    Joyce Howard says:

    How can I find out the procedure to produce the exploding pumpkin. My daughter is in 10th grade
    in the Animo South Los Angeles High School. I know
    she and her friends would love to do this in class
    with their science teacher for fun.

  2. Jeff
    Jeff says:

    Your daughter’s high school chemistry teacher can contact Flinn Scientific to purchase the materials to do the experiment. Only certified chemistry teachers can purchase from Flinn Scientific (because of liability reasons as you might imagine).

    The chemical reaction inside the pumpkin produces a small amount of acetylene gas which is ignited. The reaction is dangerous for someone to try unless they have a good chemistry background. The demo has become quite popular among chemistry teachers thanks to Flinn Scientific.

  3. Caran Wysong
    Caran Wysong says:

    My son is in 6th grade and came home with an assignment to do a science experiment in front of the class in about a month. Would it be possible for him to do the oozing pumpkin? Is the formula in one of your books? If you don’t think this would be a good choice, do you have any other cool suggestions. BTW, I love you website and the videos. I found it while searching for something for him to do.

  4. Steve
    Steve says:

    I didn’t see your post… sorry! The oozing pumpkin uses very strong hydrogen peroxide and would be dangerous outside of a controlled school setting. Dry ice dropped in warm water with a squirt of dish soap produces an interesting effect, but it’s somewhat different from the oozing pumpkin.

  5. Allison Chapman, M.S.
    Allison Chapman, M.S. says:

    I was planning on doing the H2O2 foaming at the mouth, Jack-O-Lantern with my classes and the Science Club…but then I heard about the exploding pumpkin. I’ve used a calcium carbide lantern before and use to blow a tennis ball about 20ft up in the air w/ a make-shift calcium carbide “cannon”.

    Do you have any suggestions for amounts of carbide and water to use for a good effect?

    I have a Masters of Science in Physical Chemistry but it was for computer simulations—I wasn’t in a wet lab. I teach at Palmetto Ridge High School in Naples, Fl.

    Thank you,

    Allison Joy Chapman
    Chemistry Instructor
    [email protected]

    Palmetto Ridge High School
    Chemistry Room 569
    1655 Victory Lane
    Naples, Fl 34120

    239-377-2400 x2495

  6. JYB
    JYB says:

    You only need a little carbide (tsp?). The main thing is to wait about 20 seconds or so for the gas to build.

    I seem to remember a Steve Spangler exploding pumpkin where he just tapped on the pumpkin. I have no idea how that one was done.

  7. Ben
    Ben says:

    I am a lab manager for a chemistry class, and the superintendent of my school district and I are looking at performing the exploding pumpkin experiment for a kindergarten class during Halloween. I have looked all over for some sort of detailed instructions. However, I can’t find one that says exactly how much Calcium Carbide to use, how much water to use, or even how long you need to wait for the reaction to take place. Flinn doesn’t have a write up for it, and neither does anyone else as far as I saw. Can someone give me a little help so I don’t have to do this the “trial and error” way? That could get messy…

  8. jonny
    jonny says:

    for this exploding pumpkin experiment to work, you need calcium carbide, the amount of this depends on the size of the pumpkin, but u can roughly use 2grams for a medium sized pumpkin, but its all trial and error so few experiments should be required before the actually thing. the amount of water is just enough to cover the calcium carbide. what i suggest is using tin foil and placeing the calcium carbide in then pouring water into it til it covers the calcium carbide. also you want to put a whole in the back of the pumpkin at the bottom, and for best results plug the hole with some plasterseen, then when ready light the splint(id attach this to something long to prevent injury to ur hand like a meter stick). id wait about 5-10 seconds just so the gas is formed. also when doing this experiment u wanna wear safety goggles… hope this helps. good luck 🙂

  9. Bob Kahn
    Bob Kahn says:

    I have done the exploding pumpkin demo every year for the last 15 years. I use calcium carbide and water as described above.
    I put some water in a small coffee tin and pour about a half a teaspoon of cc into the water.

    Lately though, the pumpkin does not explode but instead there is a poof and a fire inside and tons of black soot.

    Any help would be much appreciated.
    Thanks so much.


  10. Amu
    Amu says:

    Hey Bob,

    It sounds like you have an incomplete combustion reaction happening due to lack of oxygen (hence all of the black soot). Maybe try using less calcium carbide or leaving the lid open for a few second after you drop in the calcium carbide for a bit of gas exchange. Not sure if it will help, but it is a suggestion.


Trackbacks & Pingbacks

  1. […] you can find some great things to do with those leftover jack-o-lanterns after Halloween. Here is Steve Spangler’s version of an Exploding Pumpkin that carves itself. Most people just have the pumpkin shoot flame from its […]

  2. […] you can find some great things to do with those leftover jack-o-lanterns after Halloween. Here is Steve Spangler’s version of an Exploding Pumpkin that carves itself. Most people just have the pumpkin shoot flame from its […]

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