We love a good baking soda experiment. I spotted this brilliant and simple idea on Reading Confetti, who kindly said I could post it here. These are our fizzing rocks.
How to make fizzy rocks
You’ll need
Water
Bicarbonate of soda/baking soda
Vinegar
Food colouring
Instructions
Mix a little water with the bicarbonate of soda. I used a whole packet of bicarbonate of soda and added water slowly until I had a very thick paste type mixture.
Add a few drops of food colouring, mould the paste into rock shapes, and leave it to dry for a few hours.
Once the rocks have hardened, slowly add vinegar and watch as they fizz and dissolve.
The science behind baking soda rocks
Vinegar (an acid ) and bicarbonate of soda ( an alkali ) react to neutralise each other. This reaction releases carbon dioxide, a gas that causes the bubbles you see.
Other ideas
Add small objects to the rocks and drop them into a bowl of vinegar like Reading Confetti did.
Make one big rock and see how much vinegar is needed to dissolve it.
Try one of my other fantastic baking soda experiments.
Last Updated on July 16, 2025 by Emma Vanstone
Thanks for the link. Love your idea of making one big rock. We might have to try that next!
I’m glad you spotted it! We had so much fun 🙂
I like that you made your own fizzing rocks! We may have to try that sometime.
you should it was great!
Oh – this idea really does rock!!
🙂 Ha ha
Oooh this looks like great fun. Love the addition of colour.
Maggy
Thanks Maggy, it was very fun!
PS Thanks for sharing on Kids Get Crafty!
looks great fun
IT was great!
This really looks like fun!
It really was!
Try this: make a batch, make small balls out of it in one color and let it dry. Then make a second batch, make it a different color, wrap it around the first balls and let dry. When you add the vinegar, the outside fizzes away in one color, then the inside ball fizzes a second color. Next we want to try putting something inside like you suggested.
oooh that sounds fantastic! Thanks for the idea.
How fun! You guys always have the neatest experiments!!! Thanks for linking up to TGIF! Looking forward to seeing you linked up again tomorrow =-)
Beth
Thanks Beth!
Great idea! I’m going to add this to my list of fun baking soda & vinegar activities with my kids. Thank you!!!