Let’s start off with an easy experiment today. Create a colorful column with three liquids stacked on top of each other inside a test tube.
Things you’ll need: test tubes, pipet, food coloring, light or dark corn syrup, vegetable oil, and water.
- Pour about 3 ml of corn syrup into the test tube.
- Use a pipet to add 3 ml of water with food coloring (I use green). Make sure to drop the water on the side of the test tube.
- Do the same thing with vegetable oil but no water and food coloring.
- Observe the column you made. Which liquid is the least dense? Which is most dense? You could say that the liquid on the bottom has higher density. It means that the corn syrup has a high density. Medium density is water. And the vegetable oil has low density.
- What will happen if you add other liquids? Try adding apple juice, vinegar, soda, etc. You could also follow the column on the bottom.
An object’s density is determined by comparing its mass to its volume. Consider a rock and a cork that are the same sizes; the rock is denser than the cork, because it has more mass in the same volume. This is due to the atomic structure of the elements, molecules, and componds that make it up. The same is true for liquids. Although you added approximately the same volume of each liquid, they all had different densities, based on mass per volume. Water has a density of about 1.0 gram per ml of volume. Matter with higher density will sink in water; matter with lower density will float on top. Calculate the approximate density of other liquids using this formula: Density= Mass/Volume. Measure mass by calculating weight (how heavy it is). Weigh each liquid in grams (subtracting the weight of your container), the divide that number by the liquid’s volume (ml). The answer is density in grams per milliliter.
See also: The Floating Needle Experiment