Density Tower Lab

Density measures how much mass is packed into a given volume. It is calculated as mass divided by volume, expressed in grams per milliliter (g/mL) for liquids.

Liquids with higher density sink below liquids with lower density. Water has a density of 1.00 g/mL, which is used as a reference point.

• Honey: 1.42 g/mL (denser than water)
• Rubbing alcohol: 0.79 g/mL (less dense than water)
• Vegetable oil: 0.92 g/mL (floats on water)

Immiscible liquids (liquids that do not mix) separate into layers based on density. Gravity pulls the denser fluid downward, and the lighter fluid rises above it.

A liquid only mixes with another if their molecules are attracted to each other (like water and dish soap). Oil and water do not mix because oil molecules are nonpolar and water molecules are polar.

Density towers appear in many real-world situations. Ocean stratification creates distinct layers of water at different temperatures and salt concentrations. Salinity increases density, which is why the Dead Sea has such high buoyancy.

Lava lamps use the same principle. The wax has a density very close to the liquid, so small temperature changes make it rise or fall through the layers.

An object floats at the interface between a denser liquid below it and a less dense liquid above it. This is Archimedes' principle in action.

• Steel bolt (7.87 g/mL): sinks through everything
• Ping-pong ball (0.09 g/mL): floats at the very top
• Ice cube (0.92 g/mL): floats on vegetable oil
• Grape (1.06 g/mL): settles just above corn syrup