Cartesian Diver

Demonstrating gas compressibility and Boyle's law

Gas Laws Beginner (Middle School) 15 min ~$3.00

Objective

Build a Cartesian diver to demonstrate gas compressibility and the relationship between pressure and buoyancy.

Background

A Cartesian diver is a small inverted container partially filled with air, placed in a sealed bottle of water. When the bottle is squeezed, pressure increases, compressing the air in the diver, which becomes denser and sinks. Releasing the squeeze reduces pressure, the air expands, and the diver rises.

Safety Warnings

  • No significant hazards

Materials

  • Plastic bottle (1L) (1)
    With cap, clear
  • Small plastic condiment packet (1)
    Ketchup or soy sauce
  • Water (1 L)

Equipment

Scissors

Procedure

1

Fill the plastic bottle completely with water, leaving no air space.

2 min
2

Drop in the condiment packet. It should barely float (adjust by adding/removing water if needed).

3 min
3

Seal the bottle cap tightly.

1 min
4

Squeeze the bottle firmly. The diver should sink.

2 min
5

Release the squeeze. The diver should rise.

2 min
6

Experiment with different squeeze pressures to control the depth. Explain using Boyle's law and Archimedes' principle.

5 min

Expected Results

When squeezed, the air bubble in the packet compresses, the packet becomes denser than water and sinks. When released, the air expands, the packet becomes less dense and rises. This demonstrates Boyle's law (P↑ → V↓) in a tangible way.

Cleanup

Empty the bottle and recycle. The condiment packet can be discarded.

Details

Category
Gas Laws
Difficulty
Beginner (Middle School)
Duration
15 min
Est. Cost
$3.00
Steps
6
Materials
3

More Experiments

Boyle's Law Verification 40 min Charles's Law with a Balloon 30 min CO₂ and Limewater Test 20 min Diffusion Rate Comparison (Graham's Law) 30 min Gas Stoichiometry with Magnesium 40 min Hydrogen Gas Collection 35 min Molar Volume of a Gas at STP 35 min Vapor Pressure and Boiling Point 45 min

Frequently Asked Questions

What is the objective of Cartesian Diver?
Build a Cartesian diver to demonstrate gas compressibility and the relationship between pressure and buoyancy.
How difficult is Cartesian Diver?
This experiment is rated as Beginner (Middle School). It takes approximately 15 minutes to complete.
What safety precautions are needed for Cartesian Diver?
Key safety precautions include: No significant hazards.
What materials are needed for Cartesian Diver?
The main materials required are: Plastic bottle (1L), Small plastic condiment packet, Water.
What results should I expect from Cartesian Diver?
When squeezed, the air bubble in the packet compresses, the packet becomes denser than water and sinks. When released, the air expands, the packet becomes less dense and rises. This demonstrates Boyle's law (P↑ → V↓) in a tangible way.