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