Fizzing Rocks Valentine Style

What do you think these rocks are made from? They are just bicarbonate of soda ( Baking Soda ), water and food colouring.

bicarbonate of soda

  We’ve made fizzing rocks before, they are very simple, but great fun to watch. I used a heart cookie cutter to get the shape.

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.

Once again, thanks to Reading Confetti for the idea.

Author: Emma Vanstone

Science Sparks, is a site dedicated to making Science fun for kids. I’d love you to follow me on my Google Profile+.

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  1. Thanks for the link! We’re going to have to make some heart shaped rocks soon – my daughter would love it!

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  2. Such a good idea…it reminds me of a bath bomb (although I would never use vinegar and it probably wouldn’t fizz the same!)

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  3. Another great science experience! *Lovely* to have something for Valentine’s!

    Thanks for sharing on Kids Get Crafty.


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  4. I really should do more of your experiemnets and not just look and think oh great idea!

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    • Let me know if you do :-)

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      • My attempt at making these had some kind of reaction that looked like mold after a couple of days. Does baking soda mold after its mixed with food coloring and water?

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        • I think it is the type of food colouring, was yours bake stable?

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          • My food cooling was McCormick black I don’t see anywhere on it saying bake ready so maybe that is why I still am going to try this in the classroom because my 5 year old sat for a long time making the rocks fizz! Thanks for sharing!

          • Brilliant, I’m glad you liked it.

  5. We recently filled a volcano with cola and bicarbonate with incredibly messy consequences!

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  6. Can I use baking soda for this experiment?

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  1. Fizzing rocks - baking soda and vinegar | Science Sparks - [...] also have a Valentine version of this. Can you think of any other [...]

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