Fizzing rocks

We love a good baking soda experiment. I spotted this brilliant and very simple idea on Reading Confetti, who kindly said I could post about it here. These are our fizzing rocks.


Fizzing rocks

What you need:


Bicarbonate of soda/baking soda


Food colouring


Mix some water with the bicarbonate of soda, I used a whole packet of bicarbonate of soda and just added water slowly until i had a very thick paste type mixture.

Add a few drops of food colouring, mould into rock shapes and leave to dry for a few hours.

Once the rocks have hardened, add vinegar very slowly and watch as they fizz and dissolve.


Fizzing rocks


fizzing rocks

The Science bit

Vinegar (an acid ) and bicarbonate of soda ( an alkali ) react together to neutralise each other. This reaction releases carbon dioxide a gas which is 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 totally dissolve it.

We also have a Valentine version of this. Can you think of any other ideas?

Make sure you check out some of our other fun science for kids posts.

Related posts

More Baking Soda Experiments

Monster Tea Party

Baking Soda powered boat

Baking Soda Volcano

Baking Soda Popper





There are 23 comments

  1. 4th Grade Science Fun

    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.

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