How much water can a disposable nappy soak up? Find out with this experiment, and learn about the amazing world of superabsorbent polymers at the same time!
Suitable for kids aged 4+
- Zip lock bag
- Small piece of a disposal nappy (cut about a 3x3cm square)
- Food colouring (optional)
What to do:
- Put the nappy square into a zip lock bag and add some water (about enough to half cover the nappy square at the bottom of the bag). What happens?
- Add some more water. How does the nappy respond? How much water can you add before the nappy is unable to soak up the excess?
- Feel the nappy. Can you identify what is soaking up the water?
- What happens when you add salt to the nappy? Try adding some food colouring for a colourful effect. What are you left with if you leave the nappy to dry in the sun for a few days?
Why is it so?
Disposable nappies contain superabsorbent polymers that love water, just like our growing beads and instant snow. The polymer can absorb many times its weight in water and grow up to 40 times its size. This keeps baby dry and happy! Superabsorbent polymers are composed of cross-linked molecules that have a high sodium content attracting water into the polymer system through a process called osmosis.