• Rubber gloves
• Cup/glass
• Water – 100 mL
• Sodium polyacrylate (from 4 -5 disposable diapers or feminine products or buy crystals from a garden centre)

1. Wearing gloves, cut open 4 – 5 diapers or feminane products and shake the sodium polyacrylate from the middle onto a piece of paper.
2. Put the powder into the bottom of the cup.
3. Pour 100 mL of water into the cup (with sodium polyacrylate in the bottom).
4. Wait and then turn the cup upside down. The water is gone!
5. Scoop out the contents of the cup and determine what happened to the water.

• Find out exactly how much water can be absorbed by sodium polyacrylate crystals. Place the sodium polyacrylate from 1-2 diapers or feminine products in a container (~ 500 mL) and weigh both the container and crystals.
• Add water until the crystals can absorb no more. Pour of any excess water.
• Weigh the container and expanded crystals again.
• How much water was absorbed?
• How many times its own weight can sodium polyacrylate crystals absorb?
• Which brand of diaper or feminine product absorbs the most liquid?

Inside the lining of diapers and feminine products, sprinkled on the cotton, is a material called sodium polyacrylate. Sodium polyacrylate is a super-absorbant polymer and can absorb many times its own weight in water.

When water comes in contact with the powder, it rapidly swells the granules through the process of osmosis. Osmosis is the passage of water through a semi-permeable membrane from an area of low solute concentration into an area of high solute concentration.

As a result of absorbing so much water, the powder turns to a gel.

Superabsorbent polymers, like sodium polyacrylate, can absorb up to 500 times their own weight in water. Before the use of these substances, cellulose and fiber-based compounds like cotton, fluff pulp and sponges were used in diapers and female hygiene products. However, these substances can only hold up to 20 times their own weight in water and tended to release water when full. With the development of superabsorbent polymers, many technologies have been improved, not just diapers! Polyacrylamides are used in to retain water in agriculture, to prevent medical waste leakage, to protect cables and wires from water waste, and in a variety of other places.