Racing Raisins

What you need

one package of raisins

a large beaker (800ml)

carbonated water

stop clock

What to do

participants are invited to choose a raisin to drop into a large beaker of carbonated water

time how quickly the raisin sinks and rises back to the surface

participants are required to race with each other

observe the bubbles forming on the food surface during the experiment

What to do

prizes are awarded to the top three fastest times

special prizes will be given to participants who enable to explain the scientific reason behind

What is happening

a raisin is denser than water so it will initially sink

carbonated water contains carbon dioxide bubbles

rough surface creates a large surface area for the bubbles to attach to

the number of bubbles increases on the raisin, raisin and bubbles become less dense than water, and rise to the surface

What is happening

once it has risen to the surface, the bubbles burst, releasing the carbon dioxide into the air

raisin sinks again

therefore, the items that work best will have a density that is only slightly greater than that of water