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Exploding Pumpkin and other Halloween Science Experiments

Halloween is one of the most exciting times in science class because so much of the creepy, slimy, bubbly, stinky things that we associate with Halloween can be explained by science. In my class, I devote an entire lesson to the Chemistry of Halloween. I decorate the room with black lights and spider webs and get out some of the coolest science demonstrations from the store room. The goal? Get my students excited about science by showing them some amazing experiments the will never forget!

And, what good would the Chemistry of Halloween science show be without a pumpkin? In fact, what if the pumpkin would carve itself into a Jack-o-Lantern?! That would be awesome! And, that is exactly what I do.

The Self Carving Pumpkin Science Demonstration

Supplies: Pumpkin, knife, screw driver, long lighter.

Start by cleaning out a pumpkin and carefully cutting in a very simple face design. Gently push all of cut out pieces out of the pumpkin to be sure you have cut them loose but put them directly back into the hole they came out of. Make a hole in the back of the pumpkin, opposite the face, using a screw driver. The hole should be large enough to put a long lighter inside.

Next measure 1 gram Calcium Carbide and 20 ml of water. Place the 20ml plastic cup of water inside the carved out cavity of the pumpkin and add the calcium carbide. Quickly put the lid on the pumpkin and put the long lighter in the hole in the back. Count to 30.

Hold the lid tightly on the pumpkin with one hand and light the lighter with the other. The pumpkin will go BOOM and the pieces that you cut out for the face will go flying out the front. In the end, you will have a Jack-o-Lantern that you've carved with science!

The Flaming Pumpkin

Supplies: Carved pumpkin, hand sanitizer (high alcohol), lighter.

Completely cover your pumpkin with hand sanitizer of a high alcohol content. Rub the sanitizer around with your hands. Wipe your hands clean and light the outside of the pumpkin on fire! Blue flames will engulf your newly carved pumpkin as the alcohol (ethanol in most cases) burns off.

The Fire Breathing Pumpkin

Supplies: Self carved pumpkin from above, lycopodium powder, pipette (or straw), lighter.

Lycopodium is a spore from the club-moss plant. The spore is very small and remains very dry so it remains a very fine powder in almost every condition. Because it is such a fine powder, it can easily pull oxygen (and other molecules in the air) along with it when it is pushed out of a pipette or a straw. If the fine powder is directed toward a flame, the oxygen that is being pulled with the spores interacts with the flame and causes it to combust (burn) more easily. This causes a large fireball to shoot up from the lycopodium powder cloud.

To get your pumpkin to breathe fire, put a candle or dish with flammable liquid inside the pumpkin and fill a pipette with lycopodium powder (you can use a straw but will have to blow out the powder). Insert the pipette into the hole you made for the lighter during the "Self Carving Pumpkin" demonstration and quickly squeeze the pipette bulb. A fireball should shoot out of the face of your Jack-o-Lantern. This signifies the official start of the Halloween season in my classroom - all we are missing is a big bucket of trick or treat candy...

Keep on Learning! ~Craig Beals

Craig Beals visits the set of Montana This Morning on KTVQ CBS to show the world how to carve pumpkins with science!


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