MOBILE, Ala. (WKRG) — St. Patrick’s Day is just around the corner and there are many fun experiments to do with the kids! Today we are making a green lava lamp. This experiment is easy to do at home with simple materials.

Supplies: A clear glass, water, liquid food coloring, Oil, alkaline seltzer tablet

  1. Fill the clear cup with 1/3 of water
  2. Add 2 tablespoons of oil into the cup
  3. Add 10 drops of food coloring into the cup
  4. Drop the alkaline seltzer tablet in the cup and watch the lava lamp happen!

The main reason why the lava lamp works is due to density and polarity. Density is a measure of the mass per unit volume. Oil is less dense than water so it hovers on top of the water. The molecules of water are more tightly packed so they stay at the bottom. Polarity prevents the oil and water from mixing together. Water molecules are polar since they have a lopsided electrical charge and the hydrogen molecule of the atom easily attaches to other surfaces. It negative end will connect to positive ends of other molecules.

Oil molecules are non-polar so they don’t have a positive or negative charge. In result, you will notice that oil rarely mixes with many other substances. The difference in densities and polarities allows the substances to stay unmixed when the alkaline seltzer creates bubbles and causes mixing!