I first saw this demonstration back in 2017 and was amazed. A little knowledge of chemistry can explain what’s going on.
Materials:
· Latex Balloon
· Orange
· Other citrus fruits
Caution:
If you get oils from the fruit in your eyes it will sting. Adult supervision is recommended. If you peel the orange before blowing up the balloon, make sure that you wash your hands thoroughly as the oils from the orange will compromise the balloon before the experiment.
Experiment:
Fully blow up a balloon such that the skin of the balloon is taut and tie it shut. Use an orange peel and squeeze the peel toward the balloon. What happens? If nothing happens, try a different kind of balloon.
What’s happening?
Latex balloons are made out of a molecule called isoprene that has been made into very long chains called a polymer – in this case polyisoprene. These long chain polymers are aligned with each other to form the rubbery substance and they are held together tightly enough so that small molecules in the air find it difficult to travel through the spaces between them. Normal balloons will flatten over time as some of the air can diffuse out of the balloon. These isoprene molecules are made out of carbon and hydrogen and are therefore referred to as hydrocarbons.
Polyisoprene (left), a polymer chain of isoprene molecules, and the molecule limonene (right).
The orange peel contains a molecule called limonene which is also a hydrocarbon and looks very similar to the polymerized isoprene. We find that molecules that are similar to each other in their polarity, how much charge separation exists in their molecules, will mix together very well. Hydrocarbons have very little charge separation in their structure and are considered to be nonpolar. When that happens, the solid dissolves a little bit in the liquid and it allows the small air molecules to escape between those polymer chains causing the balloon to pop.
Extension:
Try other substances that might work. Will other citrus fruits work? What about fruits that don’t have citrus? How about other substances that don’t mix with water and are nonpolar (oil, WD-40, gasoline, etc.). What about using other nonlatex balloons like helium balloons?
References:
https://www.chemedx.org/blog/how-does-orange-peel-pop-balloon-chemistry-course
https://www.madaboutscience.com.au/shop/science-extra/post/balloon-popping-trick
To view past “ChemShorts for Kids” activities, go to:
https://chicagoacs.org/ChemShorts.
