Hydrogels

We use a disposable nappy to examine the superabsorbent properties of hydrogels. We add water to grains of hydrogel and watch them swell before adding salt to see the water escape.

Chemistry - Chemical Industries - Learning Points.
Hydrogels are the superabsorbent polymers found in babies' nappies.
Hydrogels become negatively charged and uncoil to hold water.
Salt removes the negative charge from the hydrogel, causing them to recoil and release water.

A Twig Experiment Film.
Let students experience real experiments in lab conditions anywhere, from setup, method all the way through to analysis and real-world application.