Using food color and an eye dropper, a kid can test if molecules move faster in hot or cold water. Attempting to mix oil and water can yield interesting results too. A kid can use an indicator made of cabbage juice to test acidity or alkalinity of household products. An experiment to probe a disposable diaper reveals water-absorbing properties of sodium polyacrylate, which is present in the padding.
In the sodium polyacrylate experiment, food-colored water is poured on the padding of the diaper. The diaper absorbs the water, and on peeling its lining, a kid can touch and feel a gel that looks like slush. Using scissors to open both sides of another dry diaper, a kid can put it in a zipped plastic bag and peel off the inside liner to help expose the cotton padding. A kid may zip the plastic bag, shake it and tilt it to the side to notice granules that settle in the bottom corner of the bag.
The granules are sodium polyacrylate. Placing 1/4 teaspoon of the granules in a cup and adding 1/4 cup of water in it produces a gel as water absorbs. The experiment proves that sodium polyacrylate has a higher water absorption capacity than other materials, according to the American Chemistry Society.