What do you think will happen if you put a raisin in a glass of water?
It will sink!
Do you think it’s possible to make raisins rise to the top and jump around?
Find out in this simple baking soda investigation.
What you need:
A pint glass
Raisins or anything else you would like to test.
Bicarbonate of Soda (Baking Soda)
Fill the glass half full with warm water.
Add two heaped teaspoons of baking soda.
Add a few raisins
Put the glass in a tray – it might overflow
Top of with white vinegar
You should see the raisins begin to rise and fall
Why do the raisins dance?
The vinegar and bicarbonate of soda react forming carbon dioxide. The carbon dioxide bubbles collect over the surface of the raisins. As carbon dioxide is lighter than water it rises to the top and takes the raisins with it. As the bubbles pop at the surface the raisins drop again, only to be covered in bubbles again at the bottom until the reaction finishes.
More Investigation Ideas
Can you find the smallest amount of baking soda and vinegar that allows the raisins to dance? Try with just one raisin and then investigate to discover if you need more to make 2 raisins dance.
Can you think of anything else this would work with? You could investigate using other dried fruits and record how well each dances.
We tried with small LEGO pieces and found that they sank when they filled with water and once the reaction started they jumped to the top, but didn’t dance around.
We then tried with small coins, but these didn’t move at all, you can see how all the bubbles of carbon dioxide have gathered on the surface though.
Another idea is to attach something to the raisins and see if they still dance.
Why do baking soda and vinegar react?
If you combine an acid ( vinegar ) and an alkali ( baking soda ) they react together to neutralise each other.
The reaction releases carbon dioxide gas, which is the bubbles you see.
More baking soda investigations