Create a Rainbow Density Tower

Materials you'll need

• 5 cups or glasses
• Graduated cylinder or tall clear container
• Syringe or pipette
• Water
• Granulated sugar
• Food coloring (5 different colors: red, orange, yellow, green, and blue)
• Spoon for stirring

 

Step-by-step tutorial

Step 1: Pour ½ cup of water into each of your five glasses. Add a different color of food coloring to each glass and stir to mix.

Step 2: Add sugar to four of the glasses and leave one glass with no sugar. Add 1 tablespoon of sugar to the second glass, 2 tablespoons to the third, 4 tablespoons to the fourth, and 6 tablespoons to the fifth. Stir each glass until the sugar is fully dissolved.

Step 3: Use your syringe or pipette to draw up the most sugary solution (6 tablespoons) and gently add it to the bottom of your graduated cylinder.

Step 4: Working from most to least sugary, slowly drop each layer in one at a time. Take your time! Squeeze the liquid in gently and carefully so you don't disturb the layers below. Add the plain water (no sugar) last.

Step 5: Watch the colors stay separated in a rainbow tower.

Learn more

Each colored layer stays separated because it has a different density. Density is a measure of how much "stuff" is packed into a space. When you dissolve sugar in water, the sugar molecules fill in the gaps between water molecules, making the solution heavier and denser. The more sugar you add, the denser that layer becomes. Denser liquids sink below less dense ones, which is why your most sugary layer sits at the bottom and your plain water floats on top. Even though all five liquids are mostly water, their different densities keep them neatly stacked like a rainbow!