Compare the density of different liquids by making a colorful density column at home! Why do some liquids sit on top of each other, and others do not? Find out with a hands-on science project that lets kids see how different liquids "stack up."
Not all liquids have the same density. But what does this mean? Scientists define density as mass divided by volume. In the same amount of space (or volume), some substances have more mass than others. A liquid or solid with with more mass compared to the same volume of another liquid or solid has a greater density. Density is determined, in part, by how big the molecules in a subtances are and how the molecules are arranged—how tightly or loosely the molecules are packed together.
One way to get hands-on with what density means—and to really see it in action—is to make a density column using different liquids from around the house. Carefully pouring just a few liquids on top of one another and seeing what happens will let students observe density in action. With additional test liquids and deliberate use of food coloring, a density column can be turned into a scientific rainbow!
In this week's family-friendly science activity, students make a mini density column using corn syrup, vegetable oil, and water. After exploring the density of the liquids, various solid objects can be dropped into the column to compare the density of solids to each other and to the liquids. Will all of the solid objects sink to the bottom? Why or why not?
The following Science Buddies activity on the Scientific American website has all the information you need to do this hands-on activity with your students at home: Stacking Liquids.
Extend the Fun!
Other liquids you and your students might try include honey, milk, dish liquid, and rubbing alcohol. Which of your liquids do you think will have the greatest density? Can you and your kids figure out how to color different liquids to make your column (or stack) of liquids appear the way you want? To arrange the liquids in a specific pattern (or like the colors of the rainbow), you will first need to determine how the density of each liquid compares to the others you will be using. Get ready for some colurful physics!
Students curious about density or interested in exploring this science characteristic further may also enjoy the following hands-on projects and ideas:
- Can Water Float on Water?
- How Much Weight Can Aluminum Foil Boats Float?
- Race Your Marbles to Discover a Liquid's Viscosity