Imagine you have a large, light balloon and a tiny, heavy lead ball. Although the lead ball is much smaller, it is heavier. It’s a bit like the liquids in our experiment. Some liquids are quite heavy for their size, others are lighter. Researchers say they have different densities. In our experiment, we will mix different liquids. The lighter liquids, those with a lower density, will float on top, just like the balloon. The heavier liquids with the higher density will sink to the bottom, like the lead ball. Did you know that the density of a liquid also changes when it is heated or cooled? Try it out and see what happens if you use warmer or colder water.
Why does fat float on soups in the form of small, round droplets? Because fat and water repel each other, the oil forms spherical shapes so that the two liquids touch each other as little as possible.
Continue your research on these questions and use other methods to find out more about how liquids move.
As you have noticed, the density of liquids plays an important role. In order for the colored water to move, it needs some chemical help. The fizzy tablets and baking soda release carbon dioxide. These gas bubbles attach themselves to the colored water. Because the gas bubbles are lighter than the oil, they rise together with the water droplets. At the surface, the gas bubbles burst and the carbon dioxide escapes into the air. As the water is now heavier than the oil, it sinks back down again.
At ISTA, Caroline Muller researches weather phenomena such as hurricanes. With the help of hurricane hunters, satellites and mathematics, the research group wants to find out how global warming affects the weather. As in the experiment, density influences whether air masses rise or sink.
