Dancing Raisins
HOW CAN YOU MAKE A RAISIN DANCE? ALL YOU NEED IS A SMALL PLASTIC BOTTLE, SPARKLING WATER, A FUNNEL AND SOME RAISINS.
EQUIPMENT
- Small 500ml plastic bottles (1 per child)
- Sparkling Water
- Packet of raisins (approx. 10 per child)
- Funnel
METHOD
- Ask the children to work in pairs. Give each pair a 500ml plastic bottle
- Using a funnel, pour sparkling water or lemonade into the bottle so that it is approximately 1/2 full
- Add around 10 raisins and watch them dance!
THE SCIENCE
The fizzy drink has carbon dioxide dissolved in it (under pressure). When we open the lid (releasing the pressure), the carbon dioxide forms bubbles of gas. Because of surface tension crushing them, bubbles do not easily form in the middle of the bottle. Instead, they tend to form on the bottom of the bottle, and on the raisins. If we look closely, we can see that the raisins have lots of wrinkles. Eventually, once the bubbles have stuck to the raisins and grown big enough, the raisins float as the bubbles rise.
When some of the bubbles pop at the surface, the raisins sink again because they are denser than the liquid drink. The ‘dance’ begins again when the raisins are raised by the bubbles that are left.
HEALTH AND SAFETY
Ensure any spillages are cleared up to prevent slips
Encourage the children not to eat the raisins!