The bubbles that you get in any fizzy drink are carbon dioxide – the same gas you get when you mix acid and baking soda in Plant Colours and Acids.

But, if you leave a bottle of fizzy drink open for too long, it will go flat -most of the carbon dioxide has come out of the drink and gone into the air. This activity lets you investigate the difference between fresh fizzy drinks and those that have gone flat……

You will need a bottle of fizzy soft drink and a sultana. Cut a sultana in half (you can also use whole sultanas, but they take a little longer to work). Pour some drink into a clear cup, then drop the piece of sultana in.

The sultana will drop to the bottom, then after a few seconds will rise to the surface. Then it will drop back down, and come up again.

Look carefully at the bubbles around the sultana. Can you see what is happening to make the sultana rise and fall?

Sultanas are good for this investigation, because they have rough surfaces which allow bubbles to collect. Try currants and raisins and pieces of other dried fruit. Do they work as well?

Try fizzy drink that has been left out for a while (so has gone flat). Does the sultana still go up and down? Does it go up and down as quickly?

Try making your own mix, using vinegar and sodium bicarbonate. Does the sultana rise and fall as quickly?

What type of career goes with investigations like these…..Food production, fashion and cosmetics

For a poem about the discovery of fizzy drinks…….Lizzie and the Bubbles

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