ChemixaLEARN CHEMISTRY

Density tower of liquids

Objective: build a layered column of household liquids ordered by density, and use floating and sinking objects to compare densities. You will pour carefully, observe the layers, and explain the stacking order with density.

Safety:

Rubbing alcohol is flammable: keep it away from stoves, flames, and sparks. Clean spills immediately because oil and soap make floors slippery. Adult supervision is required for minors. Do not drink any of the layered liquids.

Materials

  • Tall clear glass or jar
  • Honey or corn syrup
  • Dish soap
  • Water with food coloring
  • Vegetable oil
  • Rubbing alcohol with food coloring
  • Spoon
  • Small objects: grape, coin, plastic bead

Procedure

1

Start with the densest liquid

Set a tall clear glass on a tray and pour in about a quarter glass of honey.

2

Add dish soap

Slowly pour dish soap over the back of a spoon so it lands gently on the honey.

3

Layer water, oil, and alcohol

Repeat the gentle spoon-pour with colored water, then vegetable oil, then colored rubbing alcohol.

4

Observe the stack

Wait a minute and sketch or photograph the order of the layers.

5

Test floating objects

Drop in a grape, a coin, and a plastic bead one at a time and note where each settles.

What to observe

  • Each liquid forms a distinct horizontal layer instead of mixing.

  • The layers stay in the same order: honey at the bottom, alcohol on top.

  • A grape sinks through the top layers but stops above the densest ones.

  • Stirring destroys the layers; they slowly re-separate if left alone.

Why it happens

Density is mass divided by volume, and it decides whether one fluid floats on another. When you pour the liquids gently, the densest sinks to the bottom and the least dense floats on top, as long as they do not mix. Honey is the densest of the set, followed by dish soap, then water, then vegetable oil, with rubbing alcohol the lightest. Water and alcohol would mix if stirred, but poured carefully they stay layered for a while because the density difference keeps them stratified. Dropping small objects in shows density another way: a grape sinks through oil and water but may rest on the denser soap layer, because objects sink until they reach a layer denser than themselves.

Try variations

  • Predict where a cherry tomato or a paperclip will settle, then test.

  • Warm the liquids slightly and check whether the layer order changes.

  • Try salt water as an extra layer and find where it fits.