DIY Lava Lamp Oil versus Water Density Immiscibility Experiment with Alka Seltzer is a fun kids science STEM activity your preschooler or kindergartener would love.
My children have been fascinated with science so kids STEM activity has been their favorite subject because the result is usually unexpected, the activity is hands-on, utilizing many scenes, and most importantly, it is fun! So, today we are experimenting with the density of oil versus water by making a DY lava lamp.
What your child learns from this Lava Lamp: Oil vs Water Density Immiscibility Experiment:
- Subject: early Chemistry
- Skills the child is developing: mathematics, observation, and visual skills
- Concept: density, immiscibility
What you will need to conduct this kids’ science experiment:
- colored water (buy glass test tubes here and the wooden rack here)
- vegetable oil
- droppers (buy here) – I like that the silicone bulb is removable so that you can dry the inside of the dropper to prevent mold development
- Alka Seltzer (fast dissolving tablet)
DIY Lava Lamp Science mystery is revealed:
What happens to the two liquids when you add colored water to the oil?
Oil and water are two liquids that are immiscible, meaning they will not mix together since the force of attraction between the molecules of the same liquid is greater than the force of attraction between the two different liquids. So, you end up with beautiful colorful dancing bubbles in a home-made lava lamp!
For example, to make the abstract concept of density more concrete, think of two zippered plastic bags of the same size (same volume). One bag contains 10 pebbles and the other 20. The bag containing 20 pebbles is denser than the bag containing 10 because it contains more material – even though it is the same material (pebbles), thus describing the relative densities of different concentrations of the same substance. Further, imagine that a third bag has 10 very large pebbles. The volume of the material is the same, the number of molecules (pebbles) are the same, however, the third bag with large pebbles contains more material – it has a greater mass and so a greater density.
Did you know that doing laundry utilizes the concept of getting oil and water to mix? Usually, what makes our clothes dirty is grease. which contains oil. Water alone is not attracted to the oily compounds. However, detergent binds to dirt, grease, and oil because its one end is attracted to oil-like molecules. The other half of the detergent binds to water molecules, allowing the soiling agent to be washed away. Hooray! Clean clothes!
Now, what will happen to our kids STEM science experiment if we add Alka Seltzer to our “lava lamp”?
Science mystery is revealed: Alka-Seltzer tablet reacts with water to make carbon dioxide gas. These bubbles attach themselves to the colored water and cause them to float to the surface. When the bubbles pop, the color sinks back to the bottom. And, answering Julia’s question: “How come, we had mixed so many colors and the only color you see is green?” I guess, the children had added mostly the two primary colors: yellow and blue, creating a beautiful secondary color green!
Oil and water do not mix, but rather oil breaks up into small little drops, which float on the surface because water is heavier and denser than the oil. So while the water is sinking to the bottom, the oil is rising to the top, creating a beautiful display of bubbles going up and down.
When my children cannot stop saying “Wow!” and giggle, I know it was a perfect science experiment! The home-made lava lamp is a great way to entertain your children while exposing them to early chemistry. Unfortunately, this lamp does not last long.
Adult supervision is required.
For more on the property of water, see here Pour it in! Liquid Illusion.
For more on science experiments:
- See here a video-post Float or Sink Tangerine Science Experiment. Also, see here Walnut Shell Sailboats Water Science Experiment.
- For baking soda experiments: see here Magic Balloon (Baking Soda and Vinegar Reaction), and here a video-post Erupting Volcano Science Experiment 101 Series.
- Moreover, check out here Primary Colors, Water & Paper Capillary Action Timelapse Kids Science Experiment (Rainbow Walking Water).
- Lastly, for more on color-mixing, please see here Father’s Day Balloon Color-mixing DIY Craft.