Science - Lava Lamp

Would the colourful bubbles rise and fall, or stay still?
title
Lava Lamp
time
10-12 mins
image
age
8+
difficulty
Medium
hypothesis
If oil, water, and food colouring are combined, then the food colouring will sink through the oil and mix with the water because oil and water have different densities and do not mix.
material
A clear glass
material
Water
material
Vegetable oil
material
Food coloring
step

Place 1 to 2 tablespoons of baking soda flat at the bottom of your empty glass jar.

Fill the glass about ¾ full with oil.

step

Put 2 to 3 spoons of white vinegar.

step

Add 5–10 drops of food colouring.

Step
Watch the food colouring sink through the oil and mix with the water.
observation
What do you observe when the oil, water, and food colouring are added to the glass? Do the oil and water mix or remain in separate layers? What happens to the food colouring as it moves through the oil? Observe which liquid stays on top and how the coloured water settles at the bottom.
explanation
Oil and water do not mix because they have different properties and densities. Oil is less dense than water, so it floats on top, while the denser water stays at the bottom. The food colouring does not mix with the oil, so it passes through the oil and mixes with the water. This creates the interesting layered effect that makes the experiment look like a simple lava lamp.