Exploding Pumpkins

Television viewers in Denver woke up to the sounds of exploding pumpkins. It was actually a new version of my self-carving pumpkin trick for Halloween.

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

34 replies
  1. Kristina
    Kristina says:

    I am attending school as an education student, training to become an elementary teacher. One of our science assignments is to generate an expereiment that would get kids asking questions. My partner and I chose Halloween to present. I found your website and seen this experiment, and it got my interest going. However, I cannot find instructions on how to perform the experiment, what happens, and why it happens. Is there a place that I could find this information, as I would love to present to my fellow classmates this exciting experiment on Halloween. Thanks

  2. Steve
    Steve says:

    Yes, this is a great demo… but for television! The explosion inside the pumpkin comes from the iginition of acetylene gas. I first learned of the demo from a Flinn chemistry workshop at a National Science Teachers Association convention. You might find a write-up at http://www.flinnsci.com

  3. EZ
    EZ says:

    I read your response to Kristina regarding the directions for duplicating “exploding pumpkins”.
    I tried Flinn, to no avail. I would like to do this as a demonstration in our hands-on Science museum, DiscoveryWorks. Any help you can provide would be greatly appreciated.
    Thank you.

  4. Carter
    Carter says:

    Here’s how I do it with my high school chemistry students: I put about 3 grams of calcium carbide in a metal can and the can goes down into the carved out pumpkin. The carvings (the face or whatever) is carefully put back into the front of the pumpkin. Water is added to can and the mixture allowed to react – the gas being produced is acytelene. There’s a hole in the back of the pumpkin big enough for an ‘aim and flame’ striker (one of those lighters). Put the lid on the carved out pumpkin and squeeze the striker – boom! Everyone wears safety glasses, of course.

  5. Steve
    Steve says:

    If you’re a first year chemistry teacher, I would highly recommend that you contact the great people at Flinn Scientific – http://www.flinnsci.com – before doing it. They might even sell a kit with all of the necessary safety precautions. My version of the demo was done in a television studio with many safety precautions in place. Contact Flinn! (800) 452-1261

  6. Kim Kauzlarich (Flinn Scientific)
    Kim Kauzlarich (Flinn Scientific) says:

    Hello science enthusiasts!
    I just wanted to mention that the Flinn has received several phone calls regarding this activity due to the reference on this forum. This demonstration was in fact presented by a teacher at the NSTA Morning of Chemistry, however, we do not have a ChemFax! written up for this demonstration. The amounts of calcium carbide vary depending on the size of the pumpkin used, and there is also an obvious safety issue. It really takes some perfecting to achieve a “perfect exploding pumpkin”.
    Thank you for your comments Steve – keep up the great service you provide science teachers!

  7. ashley
    ashley says:

    we did the exploding pumpkin in school during science. it scared the living day ligvhts out of me. it was loud. my scienc teacher did it with the other classes and it was done outside but we could her it from inside.it was asowem.

  8. Laurie-Ann
    Laurie-Ann says:

    Is there another chemical i can use? i haven’t got any calcium carbide but would love to do this activity with my chemistry class.

  9. Jeremy
    Jeremy says:

    I am an AP Chemistry student who helped perform this experiment for my high school’s Safe Trick or Treat Night and we used an ISOPROPYL ALCOHOL mixture with PHENOLPHTHALEIN. It is highly more flammable, but the results are just as spectacular! Good Luck!

  10. Rashmi
    Rashmi says:

    I am a chemistry teacher and I want to do this experiment with ISOPROPYL ALCOHOL mixture and PHENOPHTHALEIN.Can You please guide me how much quantity of each is required?

  11. Ian
    Ian says:

    Hi I am in the 8th grade and thinking about doing this experiment I was looking at the video pretty sure i have everything but it said your supposed to cut a whole in the back and thats where you light it but wouldn’t that just #1 burn you if you were lighting it from behind? #2 wouldn’t the explosive energy just go out the back? Thank you.

  12. Steve Spangler
    Steve Spangler says:

    Hi Ian,

    It’s great to see an 8th grader with so much science ambition! However, this experiment is not one that I would recommend to anyone other than trained professionals. Ask your chemistry teacher if he/she could perform this experiment for Halloween… it’s a great reaction, but much safer when performed by an adult who is trained to work with these dangerous chemicals.


  13. Leah Rackley
    Leah Rackley says:

    I would like to do an experiment like this for my children’s church class, but I do not have access to chemicals. Is there a way to perform this experiment with everyday supplies.

  14. Bruce
    Bruce says:


    One reference above mentioned rubbing alcohol. 91% from your favorite wal store should do the trick. I have used it with great success in potato cannons, so it should do this just fine. Put it in a small spray bottle that gives a good mist so it mixes well with the air. Always try it yourself before the demo and make sure you are not alone. Fire can be a dangerous thing. I singed my bangs and eye lashes burning black widows with this set up.

  15. Cari
    Cari says:

    I am a chemistry teacher with access to all materials, but wasn’t sure if I would have to go out and buy multiple pumpkins to get the job done + I wanted to practice on Thursday to get the technique and amounts correct before demonstrating for my students. Can the same pumpkin be used multiple times or must a new one be used each time?

  16. rose
    rose says:

    I’ve got the supplies but haven’t tried it yet myself. I have looked up other people’s experiments on youtube. Some of the people playing with this stuff are working on Darwin Awards. When I do this, I will start small. I don’t want to completely blow up my pumkin on the first try but I would expect to need to have back up pumpkins… since I don’t know what I’m doing… that’s why it’s called research. Please be careful.

  17. Cari
    Cari says:

    I am being careful and I’m working with another chemistry teacher who is more experienced but regardless, I bought three pumpkins. I’m trying it today without any kids around to test with the amounts because I’m going for the eyes, nose and mouth pop-out and not pumpkin exploding guts everywhere…

  18. Susan
    Susan says:

    Let’s all take Steve’s advise and leave this experiment to teachers and professionals who have the proper ingredients and environments to perform this.

  19. Barbara
    Barbara says:

    Cari, please let me know how yours turns out. I have all the calcium carbide and the pumpkin carved, just feeling a little anxious about doing this in front of students and want to practice. Also, not sure if I will need another pumpkin or not.

  20. britny
    britny says:

    hi i am a 12th grade student currently taking chemitry, and i am doing this experiment for a grade 9 science class. this is how i am doing, and so far the reactions ive gotten it pretty good, and how my group is doing it it’s pretty safe.. 1st we carved the pumpkin to what we wanted, put the pieces back in, carvd a hole in the back. then we measure 2grams of calcium carbide (our pumpkin was medium sized) and 20ml of water, which then the water reactes with the carbide and makes a huge loud bang. we attached a buring splint (popsicle stick) to a meter stick and then lite the pumpkin that way to prevent any injuris, also we used plastercine to cover the hole we carved in the back to stop the gas forming to seep out the hole… the 1st time we did this without the plastercine and the meter stick with the splint and my friends hand got a tad burned. so we found this way to be very very useful and it prevents alot of injuries if done properly and handles with care.

  21. Cari
    Cari says:

    I tried it this morning, ended up starting with a smaller amount of calcium carbide but ended up needing between 2-2.5g. I placed the calcium carbide in a little cup I made out of aluminum foil, added just enough water to cover the calcium carbide (it fizzes at that point as the gas immediately begins to form, put the lid back on the pumpkin, blocked the hole in the back of the pumpkin with my hand, had a pre-lit candle attached to a meter stick in a safe place so that the candle was not in danger of causing a fire, counted to 10 brought the tip of the candle to the hole (me at opposite end of the meter stick), and boom, it worked perfectly. The pumpkin is on fire so to speak for a few seconds but it rapidly went out. The pieces of the pumpkin were perfectly fine afterwards so one pumpkin should work but I’m gutting out two more tonight just to have them. If anything, they become room decorations. I’m very excited to do it tomorrow. My kids will be across the room for that just in case factor but the pieces basically went out two feet from the pumpkin so I’m not too worried…. better to be safe than sorry though. Have fun… Happy Halloween!

  22. Kathy M
    Kathy M says:

    Thanks so much Cari!!!
    I have 6 carved pumpkins ready to go for 5 classes. Your description seems to be the best and it makes me feel a bit more relaxed about this demo. The kids oughta love it!! I can’t wait for 1st period!!
    More tomorrow after all my classes……… cross your fingers!
    8th Grade Science Rules!!!
    Happy Halloween to all!!!

  23. Ariana
    Ariana says:

    I am an 8th grade science teacher and would LOVE to do this experiment around Halloween for the students. I have 7 sections and was wondering if you can “reuse” the pumpkins or if you need a new one for each explosion.

    Also, can this be done in the classroom or will we need to go outside to do it? I don’t want to set off any fire-alarms (that doesn’t look too good for a first year teacher).

  24. Julie Gintzler
    Julie Gintzler says:

    Ariana – If you search for “exploding pumpkins” on our website, you’ll find a page that explains the reaction (in very general terms). As you know, we don’t put specific quantities on the website because we don’t want people to get hurt. I have to tell you that this is EXTREMELY dangerous. You should be wearing a full face shield, coat, safety gloves and safety glasses. I would strongly recommend that you do this for the first dozen practice pumpkins you blow up until you really get the hang of it. It is not our intent to be evasive, rather to protect the safety of those who use our site and are not trained in the usage of chemicals. The experiment starts with the carving of a Jack-O’Lantern and the build up of acetylene gas which is ignited. The truth is that there really is no exact recipe since each pumpkin is different and there’s always the chance that too much acetylene gas built up in the pumpkin will make the whole thing will explode! There is a set of chemical reference books called “Shakhasairi Chemical Demonstrations” series. This chemical text series is designed as a high level chemical demonstration text. You will find the full experiment details in these books. Oh… and the pumpkin can be re-uesd as long as you haven’t blown him up.

  25. Danica
    Danica says:

    Please respond to this! I’ve been trying to research the best way to dispose of the calcium carbide in the pumpkin after the explosion and can’t find anything useful!

    • Susan Wells
      Susan Wells says:

      Hi Danica – I apologize, but disposal of chemicals is not our domain. We encourage our fans to leave the hazardous stuff to the experts, like chemistry teachers. My advice is to either check with your favorite chem teacher or local and state regulations.


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