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Thursday, July 9, 2020

Colourful Witches Potion Science Experiment

Kids will watch on in awe as these bright witches potions bubble and brew to life. This colourful witches potion experiment is a fun activity to do at Halloween or for a Harry Potter or spooky themed birthday party. With a twist on the traditional bicarb and vinegar science experiment, these witches potions combine science and creepy crawlies into one spooky, fun activity kids will love.

witches potions erupting with creepy crawlies


With this magic witches potion recipe all children can experience what it's like to create potent potions in seconds. The question is will they be wicked witches or white witches? Only joking, there's no malevolence here, we're all good witches of the north.

Double, double, toil and trouble; fire burn and cauldron bubble. {Macbeth}


  • Spoon
  • Small bowl
  • Shallow tray
  • Mini cauldrons
  • Bicarb soda {baking powder}
  • White vinegar
  • Food colouring
  • Spooky creatures {bats, spiders, rats etc} 

I have a small stash of Halloween items in a box that we seem to add to each year. We don't go all out with decorating the house and don't trick or treat, but I do love all the mini decorations for play activities. Our collection includes things like mini plastic skeletons, pumpkins, creepy crawlies like spiders, rats, bats, eyeballs and fingernails, skulls etc. You can usually pick them up relatively cheap in September & October from department stores, dollar stores and even supermarkets. 

The plastic figurines are great for sensory play and small world props, we keep them and reuse them each year {just wash and dry before storing them away}. For this activity you can add any creepy crawlies you like {or none if that's not your thing}. If you want to do this activity when it's not Halloween there's usually items still regularly available on Amazon. 


To set up the witches potions, put the mini cauldrons onto the shallow tray. Fill the cauldrons half full with white vinegar. Add a few drops of food colouring into each cauldron {a different colour for each one}. You can also add some mini spiders and eyeballs inside the cauldrons.

If you want the potions to be a surprise then do this set up away from the kids so they don't know what's in each cauldron.

witches cauldron and sign on tray

When I presented the potion pots to my daughter I'd scattered some bats and rats across the tray and added a the witch is in sign. I then gave her a small bowl of bicarb soda with a spoon. It was a complete surprise to her when she added the bicarb to the cauldrons and different colours started bubbling out.


girl making a chemical reaction in a witches cauldron

When the bicarb soda {also commonly known as baking powder} touches the vinegar in the cauldron it immediately causes a chemical reaction, which results in carbon dioxide bubbles forming and erupting, to expel the gas as fast as possible. The reaction is quite quick and can bubble and foam out of the cauldron and across the tray in a few seconds, which is why it's best to set this experiment up on a tray with a lip so it doesn't flow everywhere. The cauldrons can continue to erupt by adding more bicarb, until there is no vinegar left inside.

child doing bicarb and vinegar reactions
baking powder and vinegar reactions in a mini cauldron

My big girl loved making the witches potions bubble and boil over to see which colours would erupt out. As they erupted some of the little spiders would come floating out and she could see the eyeballs spinning around inside the cauldrons. She kept making them erupt until there was no bicarb soda left. 

The tray does end up becoming a bit of a mess {and can end up a muddy brown depending what colours you use} however it's perfectly safe for kids to play with as the chemical reaction results in water and carbon dioxide {which is released through the bubbles} so the liquid is safe to touch. It's also easy to clean up by washing away under a tap. The food colouring shouldn't cause staining, however if you're worried only use 2-3 drops for each cauldron.

colourful witches potions for halloween

fizzing witches potion halloween science experiment for kids


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