Witches Brew Science Experiment

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Have fun making pretend potions with kids this Halloween season! Try this Witches Brew Science experiment. Make one cauldron or make more with different colors. You can even add biodegradable glitter to them.

RELATED: How to Make Oobleck

Kids will love learning about the science of base and acid reactions in this fun science experiment for Halloween.

For another fun Halloween experiment, try making oobleck.

The Science

What happens when you mix vinegar and baking soda?

You see the bubbling and foaming but what is causing this reaction? The baking soda (sodium bicarbonate) is a base while the vinegar is an acid and what you are seeing is an acid/base reaction. Initially, the reaction makes carbonic acid which is unstable and breaks down into carbon dioxide (CO2) and water which is what creates all of the fizzing and bubbles as the gas leaves the water. This makes fizzing action that bubbles over the cauldron!

Supplies Needed

Mini Cauldron s – you can also usually find these at the Dollar store around the Halloween season
Baking Soda – we like this large 5 lb bag for activities since it’s more economical
Water
Concentrated Food Coloring – We like to use this liquid food coloring gel since it’s concentrated and makes the colors really vibrant.
Dish Soap – any kind should work
Vinegar
Droppers or Squeeze Bottle – for squirting vinegar into the mini cauldrons
A Tray – we like these plastic white serving trays for messy experiments or sensory play

Watch the Video Tutorial

Directions

1. Add baking soda into the cauldron.

Add 1 tablespoon of baking soda into each cauldron.

2. Add water.

Add 1/2 tbsp. of water into each cauldron (this makes mixing the food coloring with the baking soda easier).

3. Add food coloring.

Add about 4 drops of concentrated food coloring into the cauldron. You want the food coloring to be very dark when mixed with the baking soda for a vibrant result.

4. Add dish soap.

Add 1 drop of regular dish soap in each cauldron. This step is optional but it make the result a little more foamy.

5. Add vinegar.

Put vinegar into a squeeze bottle. Add vinegar from the squeeze bottle into the cauldrons and they should bubble over. You can also use a small dropper or a spoon to add the vinegar in.

TIP: Add some water to the vinegar to use less vinegar!

If you find they are not bubbling over, add another tablespoon of baking soda into each cauldron. Add a bit more food coloring to keep the color vibrant.

See more science experiments:

Try making oobleck for Halloween – add to a large cauldron for a fun Halloween science activity!
Make some fluffy pumpkin slime
Make Halloween slime
Try this dancing corn experiment