We’ve always been fascinated with the elephant toothpaste experiment but were hesitant to do it because it uses hydrogen peroxide which is a chemical that isn’t always safe to use around kids. The original ingredients for it called for 30% peroxide which can cause thermal and chemical burns. Some have experimented with just a 3% version of the peroxide with good results.
We wanted to achieve a similar result, which is basically a lot of foam, without using peroxide. The original experiment uses hydrogen peroxide catalyzed by potassium iodide, which requires the use of safety gear and adult supervision.
So, in this kid-friendly version, we’re using a base reaction with an acid via a mix of baking soda with citric acid, then adding this to milk. What you get is a fast-rising, milk foam with good density. All the ingredients for this home science experiment are food safe, which makes it safe for kids 🙂
Here’s what you need:
- 2 tbsp baking soda
- 1 tbsp citric acid
- half a glass of milk in one tall container (jar or tall glass would do)
- a quarter cup of milk in a separate container
- food colouring (optional)
- a tray or cookie sheet to make clean-up easier
Here’s how to do it:
- In the half glass of milk, add 2 tbsp of baking soda and your food colouring (about a drop).
- In your quarter cup of milk, add 1 tbsp of citric acid. If you’re combining colours, add another drop of food colouring here.
- Just pour your citric acid-milk combination into your baking soda-milk combination and watch it foam!
Here’s what it looks like:
Here’s the video of our actual experiment:
Activities for Kids at Home 