Celebrate and learn with liquid ‘fireworks’ you can make at home
Discovery Place Science
Every July 4, America celebrates the anniversary and signing of the Declaration of Independence. Most Fourth of July celebrations include parades, barbeques and, of course, fireworks.
Fireworks exhibit physical and chemical changes that we all enjoy. With three main components – an oxidizer, a fuel and a chemical mixture to produce color – scientists can create some complex designs in the sky.
In this activity, we will make liquid fireworks in the jar using items you already might have in your kitchen. Thanks to a little color mixing, polarity and density, we’re going to be able to make these mini-explosions of our own!
- Mason jar
- Food coloring (2 to 3 different colors)
- Cooking oil
- Small plate
1. Fill your jar with 3/4 cup of warm water.
2. Add approximately 3-4 Tablespoons of oil to a shallow plate.
3. Pick 2-3 different colors of food coloring and add 4 drops of each color to the plate. Make sure each drop is separated from the others, so no two drops on the plate are touching.
4. Using the back of your fork, break up the drops of food coloring into smaller droplets.
5. Pour the oil and mixed food coloring into the mason jar carefully. Once the food coloring drops into the water, your “fireworks” will begin!
How it works
Oil and water cannot mix because water is made up of polar molecules and oil is made up of non-polar molecules. Oil will float at the top of the jar because it is less dense than water. Food coloring is also unable to mix with oil and is heavier than oil, so it will drop from the oil into the water. When it drops, the food coloring makes a small “explosion” as it begins to dissolve and disperses into the water!
Notice how we specified the temperature of the water used in this experiment. This is because of how diffusion works. The temperature of a substance is related to how quickly the molecules are moving. Try this again with cold water. Do you notice anything different?