Our Top 3 Halloween Chemistry Experiments

Jessica Clifton

by Jessica Clifton

28th October 2019

With Halloween nearly upon us, now is the perfect time for some spooky chemistry experiments that will blow your trick or treaters’ minds (and they’re educational, too)! There are some fun experiments around – we particularly like this glowing hand of doom punch recipe and this very realistic fake blood – but the three Halloween experiments below are our favourites.

Our Top 3 Halloween Chemistry Experiments

Halloween Chemistry Experiment 1: The Vomiting Jack O’Lantern

If it sounds gross it’s because that’s the point! This is a fairly simple experiment that makes good use of that most generic of Halloween props… the pumpkin. Our top tip – this experiment is best performed outside, which works well because the end result is great for decorating the outside of your house. 

The video below shows a television scientist explaining how he can make a Jack O’Lantern vomit. Using a reaction between hydrogen peroxide and solid potassium iodide (you can also use a saturated solution of potassium iodide) creates a foam-type texture that expands and pushes through the holes carved into your pumpkin. Watch the video to see the full effect:

Halloween Chemistry Experiment 2: Gooey Slime

Download our DIY gooey slime instruction sheet and make your very own gooey slime! All you need is:

  • Boiling water
  • A cup
  • Gelatine
  • Corn syrup
  • A teaspoon
  • A fork

And, of course, a spooky ghost impression… 

Download our DIY gooey slime instruction sheet and make your very own gooey slime

How to make gooey slime

Just fill half of the cup with boiling water and add three teaspoons of the gelatine. Soften it with the fork and add a quarter of a cup of corn syrup. Stir it again with your fork once the syrup has been added and you should be able to see slime begin to form. 

As the mixture starts to cool down, continue to add small amounts of water. The fine strands you’ll get are protein strands that allow the slime to stretch and make it sticky. Click on our gooey slime instruction sheet to download and print it for all your gooey slime needs!

Make your own gooey Halloween slime - instruction sheet

Halloween Chemistry Experiment 3: Cool Dry Ice Recipes

Dry ice is actually really simple to use in science experiments and it looks incredible – just make sure you take proper safety precautions and wear protective gloves and safety glasses. Dry ice is solidified carbon dioxide that has been compressed and cooled in extreme environments and is about 110 degrees Fahrenheit below zero. 

You can buy dry ice online, and the only other thing you need for this experiment is water. Mixing the two together creates the smokey effect, which is ideal for using around your house at Halloween. Try it:

  • Inside your pumpkin – just pour water straight into the pumpkin and add dry ice for a misty effect coming from the pumpkin’s eyes, nose, and mouth
  • Create a spooky Halloween cocktail (just don’t drink the dry ice cubes!)
  • A traditional bubbling cauldron

Halloween dry ice cocktails

For added effect, you can add a small amount of washing up liquid to the dry ice and water which will create more bubbles and a violent misting effect.



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