Do Diapers Really Absorb That Much Water?

Do diapers really absorb that much water?

Sodium polyacrylate is a “superabsorbent polymer,” meaning that it can absorb many times its weight. This is the material that is found in diapers. The polyacrylate chains are coiled up, and they stretch out when water is added, making it easy for water to associate with the negative charges that are present. This reaction is reversible by adding salt to the mixture. The salt disrupts the hydrogen bonds and makes the water leak out.

Materials

Diapers Water (lots of it) Bowl or container for holding the material Sodium polyacrylate Salt

Procedure

Part 1: 1. Open a diaper and flatten it out on a table. 2. Add water, 50-100 mL at a time until the diaper will not absorb any more water. Record how much water was used.

Part 2: 1. Add 2 grams of sodium polyacrylate to the bowl or container. 2. Add water, 50-100 mL at a time until the polymer will not absorb any more water. You may have to stir it a little bit. Record how much water was used. 3. Use your observations to make a hypothesis about how much super absorbent polymer is in a diaper based on how much it absorbed. 4. Add salt to the container and stir. Observe what happens. Does anything change if you add more salt? 5. The material can be thrown in the trash can or washed down the sink if salt has been added.

Think about how baby diapers work. In reality, do they hold this much liquid? Why or why not?